Janssens, W., Kramer, B. and Swart, A. (2017). “Be Patient When Measuring Hyperbolic Discounting: Stationarity, Time Consistency and Time Invariance in a Field Experiment”. Journal of Development Economics, 126, 77 – 90.


Hyperbolic discounting is one potential reason why savings remain low among the poor. Most evidence of hyperbolic discounting is based on violations of either stationarity or time consistency. Stationarity is violated when intertemporal choices differ for trade-offs in the near versus the more distant future. Time consistency is violated if the optimal allocation for specific dates changes over time. Both types of choice reversals may however also result from time-varying discount rates. Hyperbolic discounting is an unambiguous explanation for choice reversals only if the same individuals violate both stationarity and time consistency. Our field experiment in Nigeria examines the extent to which this is the case. The experiment measured both stationarity and time consistency for the same participants. Violations of the two rarely coincide, especially among more liquidity-constrained participants. Thus, in a context of liquidity constraints, eliciting only one type of choice reversal is insufficient to identify hyperbolic discounting.

Click here to read the full article.


Janssens, W., Goedecke, J., de Bree, G.J., Aderibigbe, S.A., Akande, T.M., Mesnard, A. (2016). The Financial Burden of Non-Communicable Chronic Diseases in Rural Nigeria: Wealth and Gender Heterogeneity in Health Care Utilization and Health Expenditures. PLoS ONE 11(11): e0166121. doi:10.1371/journal.pone.0166121


Better insights into health care utilization and out-of-pocket expenditures for non-communicable chronic diseases (NCCD) are needed to develop accessible health care and limit the increasing financial burden of NCCDs in Sub-Saharan Africa.

A household survey was conducted in rural Kwara State, Nigeria, among 5,761 individuals. Data were obtained using biomedical and socio-economic questionnaires. Health care utilization, NCCD-related health expenditures and distances to health care providers were compared by sex and by wealth quintile, and a Heckman regression model was used to estimate health expenditures taking selection bias in health care utilization into account.

The prevalence of NCCDs in our sample was 6.2%. NCCD-affected individuals from the wealthiest quintile utilized formal health care nearly twice as often as those from the lowest quintile (87.8% vs 46.2%, p = 0.002). Women reported foregone formal care more often than men (43.5% vs. 27.0%, p = 0.058). Health expenditures relative to annual consumption of the poorest quintile exceeded those of the highest quintile 2.2-fold, and the poorest quintile exhibited a higher rate of catastrophic health spending (10.8% among NCCD-affected households) than the three upper quintiles (4.2% to 6.7%). Long travel distances to the nearest provider, highest for the poorest quintile, were a significant deterrent to seeking care. Using distance to the nearest facility as instrument to account for selection into health care utilization, we estimated out-of-pocket health care expenditures for NCCDs to be significantly higher in the lowest wealth quintile compared to the three upper quintiles.

Facing potentially high health care costs and poor accessibility of health care facilities, many individuals suffering from NCCDs—particularly women and the poor—forego formal care, thereby increasing the risk of more severe illness in the future. When seeking care, the poor spend less on treatment than the rich, suggestive of lower quality care, while their expenditures represent a higher share of their annual household consumption. This calls for targeted interventions that enhance health care accessibility and provide financial protection from the consequences of NCCDs, especially for vulnerable populations.

Click here to read the full article.

I. Bonfrer, E. Gustafsson-Wright, (2016), "Health shocks, coping strategies and foregone healthcare among agricultural households in Kenya", Global Public Health, 10, 1, 1 - 22


Risks are a central part of life for households in low-income countries and health shocks in particular are associated with poverty. Formal mechanisms protecting households against the financial consequences of shocks are largely absent, especially among poor rural households. Our aim is to identify the relative importance of health shocks and to explore factors associated with coping behaviour and foregone care. We use a cross-sectional survey among 1226 randomly selected agricultural households in Kenya. In our sample, illness and injury shocks dominate all other shocks in prevalence. Almost 2% of households incurred catastrophic health expenditure in the last year. Using a probit model we identified the main coping strategies associated with facing a health shock: (1) use savings, (2) sell assets and (3) ask for gifts or loans. One in five households forewent necessary care in the last 12 months. We conclude that health shocks pose a significant risk to households. Implementing pre-payment or saving mechanisms might help protect households against the financial consequences of ill health. Such mechanisms, however, should take into account the competing shocks that agricultural households face, making it almost impossible to reserve a share of their limited resources for the protection against health shocks only.

Dabalen, A., Etang, A., Hoogeveen, J., Mushi, E., Schipper, Y., von Engelhardt, J. (2016), "Mobile Phone Panel Surveys in Developing Countries : A Practical Guide for Microdata Collection", Directions in Development--Poverty, Washington, DC: World Bank. © World Bank.


Household survey data are very useful for monitoring living conditions of citizens of any country. In developing countries, a lot of this data are collected through “traditional” face-to-face household surveys. Due to the remote and dispersed nature of many populations in developing countries, but also because of the complex nature of many survey questionnaires, collection of timely welfare data has often proved expensive and logistically challenging. Yet, there is a need for faster, cheaper to collect, lighter, more nimble data collection methods to address data gaps between big household surveys. The recent proliferation of mobile phone networks has opened new possibilities. By combining baseline data from a traditional household survey with subsequent interviews of selected respondents using mobile phones, this facilitates welfare monitoring and opinion polling almost real time. The purpose of this handbook is to contribute to the development of the new field of mobile phone data collection in developing countries. The handbook documents how this innovative approach to data collection works, its advantages and challenges. The handbook draws primarily from the authors’ first-hand experiences with mobile phone surveys in Africa and also benefits from experiences elsewhere. It is intended to serve a diverse audience including those involved in collecting (representative) data using mobile phones, and those using data collected through this approach. For those who will be implementing a mobile phone panel survey, the different chapters guide them through every stage of the implementation process. For potential users of the data collected via mobile phone technology, the handbook presents a new approach to data collection which they can use for monitoring programs and facilitate almost real time decision-making. A further purpose of this book is to contribute to the debate regarding the advantages of the method as well as the challenges associated with it.

Click here for the guide.



De Ree, J., Muralidharan,K., Pradhan, M.P., Rogers, H., (2015). “Double for Nothing? Experimental Evidence on the Impact of an Unconditional Teacher Salary Increase on Student Performance in Indonesia”, NBER Working Paper No. 21806


How does a large unconditional increase in salary affect employee performance in the public sector? We present the first experimental evidence on this question in the context of a unique policy change in Indonesia that led to a permanent doubling of base teacher salaries. Using a largescale randomized experiment across a representative sample of Indonesian schools that accelerated this doubling of pay for teachers in treatment schools, we find that the doubling of pay significantly improved teacher satisfaction with their income, reduced the incidence of teachers holding outside jobs, and reduced self-reported financial stress. Nevertheless, after two and three years, the doubling in pay led to no improvements in measures of teacher effort, and had no impact whatsoever on student learning outcomes. Thus, contrary to the predictions of various efficiency wage models of employee behavior (including gift-exchange, reciprocity, and reduced shirking), as well as those of a model where effort on pro-social tasks is a normal good with a positive income elasticity, we find that large unconditional increases in salaries of incumbent teachers had no meaningful positive impact on student learning.

Click here to go to the NBER website and here for the most recent version of the paper.


Jones, S., Schipper, Y. (2015). “Does family background matter for learning in East Africa?”, Africa Education Review, 12:1, 7-27, DOI: 10.1080/18146627.2015.1036540


The extent to which differences in family background characteristics explain differences in learning outcomes between children captures the extent of equality in educational opportunities. This study uses large-scale data on literacy and numeracy outcomes for children of school age across East Africa (Kenya, Tanzania and Uganda) to investigate the contribution of family background to learning differences. We find that learning differences between children from less-advantaged households and those from more-advantaged households equals around one year or more of effective learning on average. Even so, family background does not fully explain why children of school starting age display large differences in learning between countries.

Click here to go to the website of Africa Education Review.


Berry, J., Karlan, D., Pradhan, M. (2015). "The Impact of Financial Education for Youth in Ghana, Tinbergen Institute Discussion Paper, TI 2015-043/V


We evaluate, using a randomized trial, two school-based financial literacy education programs in government-run primary and junior high schools in Ghana. One program integrated financial and social education, whereas the second program only offered financial education. Both programs included a voluntary after-school savings club that provided students with a locked money box. After nine months, both programs had significant impacts on savings behavior relative to the control group, mostly because children moved savings from home to school. We observed few other impacts. We do find that financial education, when not accompanied by social education, led children to work more compared to the control group, whereas no such effect is found for the integrated curriculum; however, the difference between the two treatment effects on child labor is not statistically significant.

Click here to view paper.

Koster, W., M. Groot Bruinderink, W. Janssens (2015). "Empowering women or Pleasing Men? Analyzing Male Views on Female Condom Use in Zimbabwe, Nigeria and Cameroon". International Perspectives on Sexual and Reproductive Health, 41(3), 126–135, doi: 10.1363/4112615


CONTEXT: Usage rates of female condoms are low throughout Sub-Saharan Africa. Programs have traditionally presented female condoms as a means of women’s empowerment. However, prevailing gender norms in Sub-Saharan Africa assign sexual decision making to men, suggesting that male acceptance is imperative for increased use.

METHODS: In 2011, data on perceptions of and experiences with female condom use were collected from 336 men in Zimbabwe, Nigeria and Cameroon through 37 focus group discussions and six in-depth interviews; participants also completed pre–focus group discussion questionnaires. The data were analyzed by country, using thematic content analysis. Results were stratified by marital status and regularity of female condom use.

RESULTS: Perceived advantages of female condoms over other protection methods were enhanced pleasure, effectiveness and lack of side effects. Single and married men preferred using female condoms with stable rather than casual partners, and for purposes of contraception rather than protection from infections. In Cameroon and Nigeria, where contraceptive rates are lower than in Zimbabwe, men favored female condoms as a contraceptive device. Its acceptability as a method of protection from HIV infection is greater in highly AIDS-affected Zimbabwe than in the other two countries. In Cameroon, some men did report regular use of female condoms in casual encounters. Initiation of female condom use by men’s stable partners was not acceptable in any of the countries.

CONCLUSION: The findings suggest the importance of accounting for local contexts and targeting both men and women in campaigns to promote female condom use.

C.T.M. Elbers, J.W. Gunning, (2015), "What Do Development NGOs Achieve?", in C. Monga and J.Y. Lin (eds), The Oxford Handbook of Africa and Economics, Vol II: policies and practices, p 629 - 640. Oxford: Oxford UP.

This publication is a book chapter in: Monga C, Lin JY, eds. The Oxford Handbook of Africa and Economics: Volume 2: Policies and Practices. Oxford University Press; 2015.


This chapter evaluates the effectiveness of development non-governmental organizations (NGOs) in Africa based on randomized control trials (RCTs). It considers the arguments against the use of RCTs to assess whether NGOs are effective in development by focusing on their three main activities: capacity building, advocacy, and service delivery. It challenges the notion that there is very little scope for rigorous evaluation of capacity building and advocacy activities of NGOs and argues that the case for RCT evaluation NGOs is overstated. More specifically, the article suggests that RCTs may not produce useful estimates owing to the non-hierarchical of organization of NGOs, and instead calls for greater reliance on observational instead of experimental data.

(Retrieved 27 Jan. 2016, from Oxford Handbooks Online.)


Elbers, C.T.M. and J.W. Gunning (2014), "Evaluation of Development Programs: Randomized Controlled Trials or Regressions?", World Bank Economic Review, 28(3), 432 - 445.


Can project evaluation methods be used to evaluate programs: complex interventions involving multiple activities? A program evaluation cannot be based simply on separate evaluations of its components if interactions between the activities are important. In this paper a measure is proposed, the total program effect (TPE), which is an extension of the average treatment effect on the treated (ATET). It explicitly takes into account that in the real world (with heterogeneous treatment effects) individual treatment effects and program assignment are often correlated. The TPE can also deal with the common situation in which such a correlation is the result of decisions on (intended) program participation not being taken centrally. In this context RCTs are less suitable even for the simplest interventions. The TPE can be estimated by applying regression techniques to observational data from a representative sample from the targeted population. The approach is illustrated with an evaluation of a health insurance program in Vietnam. JEL codes: C21, C33, O22

Jones, S., Schipper, Y., Ruto, S., Rajani, R. (2014),"Can your child read and count? Measuring learning outcomes in East Africa", Journal of African Economies, 23(5), 643-672.


The last 15 years have seen major changes to education systems in East Africa. Superficially, there is much to commend. Net primary enrolment rates have risen to over 90% alongside significant improvements in gender equity. Nonetheless, there are growing concerns that better access is not adding up to more learning. This paper introduces unique test score data collected by Twaweza’s Uwezo initiative for over 600,000 children across East Africa, including children enrolled and not enrolled in school. Using these data we show that many children in Kenya, Tanzania and Uganda remain functionally illiterate or innumerate, despite having completed multiple years of school.


Hendriks, M., E.J.E. Gustafsson-Wright, F.W. Wit, T.M. Akande, B. Kramer, G.K. Osagbemi, Z. Tanovic, L.M. Brewster, J.M. Lange and C. Schultsz (2014), "Effect of Health Insurance and Facility Quality Improvement on Blood Pressure in Adults With Hypertension in Nigeria A Population-Based Study", JAMA Internal Medicine, 174(4), 555 - 563.


IMPORTANCE Hypertension is a major public health problem in sub-Saharan Africa, but the lack of affordable treatment and the poor quality of health care compromise antihypertensive treatment coverage and outcomes.

OBJECTIVE To report the effect of a community-based health insurance (CBHI) program on blood pressure in adults with hypertension in rural Nigeria.

DESIGN, SETTING, AND PARTICIPANTS We compared changes in outcomes from baseline (2009) between the CBHI program area and a control area in 2011 through consecutive household surveys. Households were selected from a stratified random sample of geographic areas. Among 3023 community-dwelling adults, all nonpregnant adults (aged18 years) with hypertension at baseline were eligible for this study.

INTERVENTION Voluntary CBHI covering primary and secondary health care and quality improvement of health care facilities.

MAIN OUTCOMES AND MEASURES The difference in change in blood pressure from baseline between the program and the control areas in 2011, which was estimated using difference-in-differences regression analysis.

RESULTS Of 1500 eligible households, 1450 (96.7%) participated, including 564 adults with hypertension at baseline (313 in the program area and 251 in the control area). Longitudinal data were available for 413 adults (73.2%) (237 in the program area and 176 in the control area). Baseline blood pressure in respondents with hypertension who had incomplete data did not differ between areas. Insurance coverage in the hypertensive population increased from 0% to 40.1%in the program area (n = 237) and remained less than 1% in the control area (n = 176) from 2009 to 2011. Systolic blood pressure decreased by 10.41 (95%CI, −13.28 to −7.54)mmHg in the program area, constituting a 5.24 (−9.46 to −1.02)–mm Hg greater reduction compared with the control area (P = .02), where systolic blood pressure decreased by 5.17 (−8.29 to −2.05)mmHg. Diastolic blood pressure decreased by 4.27 (95%CI, −5.74 to −2.80)mmHg in the program area, a 2.16 (−4.27 to −0.05)–mm Hg greater reduction compared with the control area, where diastolic blood pressure decreased by 2.11 (−3.80 to −0.42)mmHg (P = .04).

CONCLUSIONS AND RELEVANCE Increased access to and improved quality of health care through a CBHI program was associated with a significant decrease in blood pressure in a hypertensive population in rural Nigeria. Community-based health insurance programs should be included in strategies to combat cardiovascular disease in sub-Saharan Africa.

Janssens, W., J. van der Gaag, T.F. Rinke de Wit and Z. Tanovic (2014), “Refusal bias in the measurement of HIV prevalence”, Demography, 51(3), 1131 - 1157.


In 2007, UNAIDS corrected estimates of global HIV prevalence downward from 40million to 33million based on amethodological shift fromsentinel surveillance to population-based surveys. Since then, population-based surveys are considered the gold standard for estimating HIV prevalence. However, prevalence rates based on representative surveys may be biased because of nonresponse. This article investigates one potential source of nonresponse bias: refusal to participate in the HIV test. We use the identity of randomly assigned interviewers to identify the participation effect and estimate HIV prevalence rates corrected for unobservable characteristics with a Heckman selection model. The analysis is based on a survey of 1,992 individuals in urban Namibia, which included an HIV test.We find that the bias resulting from refusal is not significant for the overall sample. However, a detailed analysis using kernel density estimates shows that the bias is substantial for the younger and the poorer population. Nonparticipants in these subsamples are estimated to be three times more likely to be HIV-positive than participants. The difference is particularly pronounced for women. Prevalence rates that ignore this selection effect may be seriously biased for specific target groups, leading to misallocation of resources for prevention and treatment.

Janssens, W. and C. Rosemberg (2014), “The impact of a Caribbean home-visiting child development program on cognitive skills”, Economics of Education Review, 39, 22 - 37.


This paper provides a short-term impact evaluation of a home-visiting Early Child Development (ECD) program in the Caribbean aimed at vulnerable children from birth to three years. The analysis is based on a quasi-experimental research design including approximately four hundred children in treatment and comparable control communities. The differences-in-differences methodology estimates intention-to-treat effects. One year after implementation, we find no significant effects on the cognitive development of the average child, but pronounced differences by birth cohort. The program has significantly improved Fine Motor Skills and Visual Reception scores, related to early reading and writing abilities, of the youngest children aged below 18 months at program start. There is no program impact on the older cohort, whose cognitive development appears to be more strongly correlated with center-based ECD services. Language development has not improved for either cohort. The findings suggest that an early window of opportunities may exist for home-based programs.

Pradhan, M. and J. de Ree (2014). "Improving Education Services: District Governance and Student Learning in Indonesia". In Deolalikar, A.B., S. Jha , P.F. Quising (Eds.), Governance In Developing Asia: Public Service Delivery and Empowerment (pp. 208 - 228). Northampton, MA: Edward Elgar.


We document the likely importance of district governance and teacher management policies in relation to student learning in Indonesian primary schools. As the responsibility to deliver primary education has been decentralized to district governments, we expect district-specifi c variations in teacher management policies. Consequently, we also expect variations in learning trajectories across districts. We document substantial heterogeneity in learning gains across districts. Furthermore, we show that schools with more active teacher working groups and higher-qualifi ed teachers achieve better learning gains. However, teacher management policy variables, including school budgets, participation rates in teacher working groups, or student–teacher ratios, can explain only a fraction of the diff erences in learning across districts. It is likely that the “quality” of operation matters. More detailed measurement is needed to further understanding of the heterogeneity in performance.

Pradhan, M.P., D. Suryadama, A. Beatty, M. Wong, A. Gaduh, A. Alishjabana and R.P. Artha (2014), "Improving educational quality through enhancing community participation: results from a randomized field experiment in Indonesia", American Economic Journal: Applied Economics, 6(2), 105-126.


We present results from a field experiment aimed at strengthening school committees, and subsequently improving learning outcomes, in Indonesian public schools. School committees in treatment schools receive a grant plus a combination of three interventions: training, democratic election of school committee members, or facilitated collaboration between the school committee and the village council (called linkage). We find that measures that reinforce existing school committees, grant and training, demonstrate limited effects; while measures that foster ties between school committees and other parties, linkage and election, lead to greater engagement by education stakeholders and in turn to learning.

Zhou, F. and R. Oostendorp (2014), "Measuring the true sales of firms with matched survey and tax office data", The Review of Economics and Statistics, 96(3), 563 - 576.


This paper uses firm-level survey data matched with official tax records to estimate the unobserved true sales of formal firms in Mongolia. Taking into account firm-level incentives to comply with taxes and a production function technology linking unobserved true sales with observable firm-level production characteristics, we derive a multipleindicators, multiple-causes model predicting true sales. We find that firms underreport sales to the tax office by 38.6%, but firm-level survey data also suffer from significant underreporting. Finally, we compare our approach with two alternative approaches of measuring underreporting and discuss the practical implications of the findings for firm-level analyses of underreporting.


Günther, I. and Y. Schipper (2013). "Pumps, Germs and Storage: The impact of improved water containers on water quality and health". Health Economics, 22(7): 757–774


Applying a randomized controlled trial, we study the impact of improved water transport and storage containers on the water quality and health of poor rural households. The results indicate that improved household water infrastructure improves water quality and health outcomes in an environment where point-of-source water quality is good but where recontamination is widespread, leading to unsafe point-of-use drinking water. Moreover, usage rates of 88% after 7 months are encouraging with regard to sustainable adoption. Our estimates suggest that the provision of improved household water infrastructure could ‘keep clean water clean’ at a cost of only 5% of the costs of providing households with improved public water supply. Given the general consensus in the literature that recontamination of water from improved public sources is a severe public health problem, improved transport and storage technologies appear to be an effective low-cost supplement to the current standard of financing public water supply for poor rural communities.

Alatas, H., S. Brinkman, M.C. Chang, T. Hadiyati, D. Hartono, A. Hasan, M. Hyson, H. Jung, A. Kinnell, M. Pradhan and R. Roesli (2013). "Early Childhood Education and Development Services in Indonesia". In D. Suryadarma and G. Jones (Eds.), Education in Indonesia (pp. 82 - 108). Pasir Panjang, Singapore: Institute of Southeast Asian Studies.

This publication is a book chapter in: Suryadarma, D. and G. Jones (2013). Education in Indonesia. Pasir Panjang, Singapore: Institute of Southeast Asian Studies. Book is available at: https://bookshop.iseas.edu.sg/publication/1852.

Oostendorp, R. and Q. H. Doan (2013), "Have the Returns to Education Really Increased in Vietnam? Wage versus Employment Effect", Journal of Comparative Economics, 41(3), 923 - 38.


Many studies have analyzed changes in the returns to education in globalizing economies using the Mincerian framework. These studies have typically estimated the returns to education in terms of changes in wages rather than employment, effectively ignoring the fact that during globalization not only wages but also employment patterns are affected. In this paper we use four large-scale representative household surveys from the transition economy Vietnam for the period 1998–2006 to estimate the returns to education taking into account both changes in wages and employment. The results show that the estimated increases in returns to education are lower once changes in employment patterns are taken into account.

Pradhan, M.P., S.A. Brinkman, A. Beatty, A. Maika, E. Satriawan, J. de Ree and A. Hasan (2013), "Evaluating a community-based early childhood education and development program in Indonesia: study protocol for a pragmatic cluster randomized controlled trial with supplementary matched control group", Trials, 14(259).


Background: This paper presents the study protocol for a pragmatic cluster randomized controlled trial (RCT) with a supplementary matched control group. The aim of the trial is to evaluate a community-based early education and development program launched by the Government of Indonesia. The program was developed in collaboration with the World Bank with a total budget of US$127.7 million, and targets an estimated 738,000 children aged 0 to 6 years living in approximately 6,000 poor communities. The aim of the program is to increase access to early childhood services with the secondary aim of improving school readiness.

Methods/Design: The study is being conducted across nine districts. The baseline survey contained 310 villages, of which 100 were originally allocated to the intervention arm, 20 originally allocated to a 9-month delay staggered start, 100 originally allocated to an 18-month delay staggered start and 90 allocated to a matched control group (no intervention). The study consists of two cohorts, one comprising children aged 12 to 23 months and the other comprising children aged 48 to 59 months at baseline. The data collection instruments include child observations and task/game-based assessments as well as a questionnaire suite, village head questionnaire, service level questionnaires, household questionnaire, and child caretaker questionnaire. The baseline survey was conducted from March to April 2009, midline was conducted from April to August 2010 and endline conducted early 2013. The resultant participation rates at both the district and village levels were 90%. At the child level, the participation rate was 99.92%. The retention rate at the child level at midline was 99.67%.

Discussion: This protocol paper provides a detailed record of the trial design including a discussion regarding difficulties faced with compliance to the randomization, compliance to the dispersion schedule of community block grants, and procurement delays for baseline and midline data collections. Considering the execution of the program and the resultant threats to the study, we discuss our analytical plan and intentions for endline data collection.

Trials registration: Current Controlled Trials ISRCTN76061874

Pradhan, M.P., J. de Ree and R.J.M. Alessie (2013), "The price and utility dependence of equivalence scales: Evidence from Indonesia", Journal of Public Eonomics, 97, 272 - 281.


The purpose of this research is to estimate equivalence scales and evaluate their price and utility dependencies. To do this we unify two strands of the empirical literature on this topic, one that relies on demand data and one that relies on subjective evaluations of wellbeing. This way we are able to employ the strengths of both kinds of information. Equivalence scales are not identified from demand data alone. This is because changes in demographics could affect wellbeing directly, i.e., in ways that are not revealed by changes in behavior. The demand-based literature rules out such effects a priori and restricts parameters that measure them. In this paper we do not rely on such restrictions and instead use subjective evaluations of wellbeing as an additional source of information. Because demand data are highly informative about some of the other parameters of the model its use increases efficiency. This becomes critical once we specify complex preference structures that allow for the equivalence scale’s dependence on price and utility. Our model nests the typical models used in the subjective and the demand literature and we are able to test down both kinds. We find evidence for direct utility effects. This rejects the validity of some of the restrictions applied by the demand literature within the Indonesian context. We estimate equivalence scales that are of reasonable magnitude and decrease in utility. We also find that the scales increase in the food to nonfood price ratio for poor households, whereas we do not find price dependence for more affluent households.

Tijdens, K.G., D. Vries and S. Steinmetz (2013). "Health Workforce Remuneration: comparing wage levels, ranking and dispersion of 16 occupational groups in 20 countries using survey data". Human Resources for Health, 11(11), 1 - 11.


Background: This article represents the first attempt to explore remuneration in Human Resources for Health
(HRH), comparing wage levels, ranking and dispersion of 16 HRH occupational groups in 20 countries (Argentina, Belarus, Belgium, Brazil, Chile, Colombia, the Czech Republic, Finland, Germany, India, Mexico, the Netherlands, Poland, Russian Federation, Republic of South Africa (RSA), Spain, Sweden, Ukraine, United Kingdom (UK), and United States of America (USA)). The main aim is to examine to what extent the wage rankings, standardized wage levels, and wage dispersion are similar between the 16 occupational groups and across the selected countries and what factors can be shown to be related to the differences that emerge.
Method: The pooled data from the continuous, worldwide, multilingual WageIndicator web survey between 2008
and 2011 (for selected HRH occupations, n=49,687) have been aggregated into a data file with median or mean
remuneration values for 300 occupation/country cells. Hourly wages are expressed in standardized US Dollars (USD), all controlled for purchasing power parity (PPP) and indexed to 2011 levels.
Results: The wage ranking of 16 HRH occupational groups is fairly similar across countries. Overall Medical Doctors have the highest and Personal Care Workers the lowest median wages. Wage levels of Nursing & Midwifery Professionals vary largely. Health Care Managers have lower earnings than Medical Doctors in all except six of the 20 countries. The largest wage differences are found for the Medical Doctors earning 20 times less in Ukraine than in the US, and the Personal Care Workers, who earn nine times less in the Ukraine than in the Netherlands. No support is found for the assumption that the ratio across the highest and lowest earning HRH occupations is similar between countries: it varies from 2.0 in Sweden to 9.7 in Brazil. Moreover, an increase in the percentage of women in an occupation has a large downward effect on its wage rank.
Conclusions: This article breaks new ground by investigating for the first time the wage levels, ranking, and dispersion of occupational groups in the HRH workforce across countries. The explorative findings illustrate that the assumption of similarity in cross-country wage ranking holds, but that wage dispersion and wage levels are not similar. These findings might contribute to the policies for health workforce composition and the planning of healthcare provisions.


Hendriks, M.E., F.W.N.M. Wit, M.T.L. Roos, L.M. Brewster, T.M. Akande, I.H. de Beer, S.G. Mfinanga, A.M. Kahwa, P. Gatongi, G. van Rooy, W. Janssens, J. Lammers, B.n. Kramer, I. Bonfrer, E. Gaeb, J. van der Gaag, T. Rinke de Wit, J.M.A. Lange and C. Schultz (2012), "Hypertension in Sub Saharan Africa: Cross-Sectional Surveys in Four Rural and Urban Communities", PLoS One, 7(3), 1 - 10.


Background: Cardiovascular disease (CVD) is the leading cause of adult mortality in low-income countries but data on the prevalence of cardiovascular risk factors such as hypertension are scarce, especially in sub-Saharan Africa (SSA). This study aims to assess the prevalence of hypertension and determinants of blood pressure in four SSA populations in rural Nigeria and Kenya, and urban Namibia and Tanzania.

Methods and Findings: We performed four cross-sectional household surveys in Kwara State, Nigeria; Nandi district, Kenya; Dar es Salaam, Tanzania and Greater Windhoek, Namibia, between 2009–2011. Representative population-based samples were drawn in Nigeria and Namibia. The Kenya and Tanzania study populations consisted of specific target groups. Within a final sample size of 5,500 households, 9,857 non-pregnant adults were eligible for analysis on hypertension. Of those, 7,568 respondents $18 years were included. The primary outcome measure was the prevalence of hypertension in each of the populations under study. The age-standardized prevalence of hypertension was 19.3% (95%CI:17.3–21.3) in rural Nigeria, 21.4% (19.8–23.0) in rural Kenya, 23.7% (21.3–26.2) in urban Tanzania, and 38.0% (35.9–40.1) in urban Namibia. In individuals with hypertension, the proportion of grade 2 ($160/100 mmHg) or grade 3 hypertension ($180/110 mmHg) ranged from 29.2% (Namibia) to 43.3% (Nigeria). Control of hypertension ranged from 2.6% in Kenya to 17.8% in Namibia. Obesity prevalence (BMI $30) ranged from 6.1% (Nigeria) to 17.4% (Tanzania) and together with age and gender, BMI independently predicted blood pressure level in all study populations. Diabetes prevalence ranged from 2.1% (Namibia) to 3.7% (Tanzania).

Conclusion: Hypertension was the most frequently observed risk factor for CVD in both urban and rural communities in SSA and will contribute to the growing burden of CVD in SSA. Low levels of control of hypertension are alarming. Strengthening of health care systems in SSA to contain the emerging epidemic of CVD is urgently needed.

Kruse, I., M.P. Pradhan and R.A. Sparrow (2012), "Marginal benefit incidence of public health spending: Evidence from Indonesian sub-national data", Journal of Health Economics, 31(1), 147 - 157.


We examine the marginal effects of decentralized public health spending by incorporating estimates of behavioural responses to changes in health spending in benefit incidence analysis. The analysis is based on a panel dataset of 207 Indonesian districts over the period from 2001 to 2004. We show that district public health spending is largely driven by central government transfers, with an elasticity of around 0.9. We find a positive effect of public health spending on utilization of outpatient care in the public sector for the poorest two quartiles. We find no evidence that public expenditures crowd out utilization of private services or household health spending. Our analysis suggests that increased public health spending improves targeting to the poor, as behavioural changes in public health care utilization are pro-poor. Nonetheless, most of the benefits of the additional spending accrued to existing users of services, as initial utilization shares outweigh the behavioural responses.

Pouw, N.R.M. and C.T.M. Elbers (2012), "Modelling Priority Patterns in Asset Acquisition. The case of smallholder farmer in three rural districts in Uganda", Journal of Development Studies, 48(9), 1360 - 1374.


Poor smallholder farmers in Uganda live at or below subsistence level. They are vulnerable to multiple risks and insecurities and have limited access to capital markets. In this article we propose a model to estimate household priority patterns in asset acquisition using cross-section data. The model is applied to a field-survey consisting of 938 farm households from three districts. The model predicts the distribution of asset ownership, conditional on the type of assets owned. Based on the established priority patterns the article proposes a low-cost, regional poverty monitoring instrument using only asset type data.

Oostendorp, R. and F. Zaal (2012), "Land acquisition and the Adoption of Soil and Water Conservation Techniques: A Duration Analysis for Kenya and The Philippines", World Development, 40(6), 1240 - 1254.


This paper analyzes the adoption behavior of smallholder farmers using comparable plot-level duration data for Kenya and The Philippines. We find that adoption behavior is strongly linked to the process of land ownership transfer. This relationship is found both for data from Kenya and The Philippines and is robust to the inclusion of observed and unobserved village, household, plot, and time factors. While previous studies on adoption using duration or panel data have focused on the role of various changing villageand household-level factors, no previous adoption study has emphasized the crucial role of land ownership changes. As a corollary, the paper argues that policy-makers should look at the role of land market dynamics for investment in land.

Van der Gaag, J. and V. Stimac (2012), "How can we increase resources for health in the developing world? Is (subsidized) voluntary health insurance the answer?", Health Economics, 21, 55 - 61.

In this short note, we will take a closer look at the impact of ODA for health on per capita health spending at the country level. Our results suggest the existence of significant crowding out effects. We then ask how these crowding out effects can (at least in part) be avoided and put (subsidized) voluntary health insurance forward asa possible solution. We will discuss the significant implementation problems inherent in rolling out voluntary health insurance in low-income countries and conclude with some suggestions on how to move forward.

Van der Gaag, J., J. Shonkoff, L. Richter and Z. Bhutta (2012), "An Integrated Scientific Framework for Child Survival and Early Childhood Development", Pediatrics, 129(2), 1 - 13.


Building a strong foundation for healthy development in the early years of life is a prerequisite for individual well-being, economic productivity, and harmonious societies around the world. Growing scientific evidence also demonstrates that social and physical environments that threaten human development (because of scarcity, stress, or instability) can lead to short-term physiologic and psychological adjustments that are necessary for immediate survival and adaptation, but which may come at a significant cost to long-term outcomes in learning, behavior, health, and longevity. Generally speaking, ministries of health prioritize child survival and physical well-being, ministries of education focus on schooling, ministries of finance promote economic development, and ministries of welfare address breakdowns across multiple domains of function. Advances in the biological and social sciences offer a unifying framework for generating significant societal benefits by catalyzing greater synergy across these policy sectors. This synergy could inform more effective and efficient investments both to increase the survival of children born under adverse circumstances and to improve life outcomes for those who live beyond the early childhood period yet face high risks for diminished life prospects.

Van Klaveren, M. and K. Tijdens (2012). "Empowering Women in Work in Developing Countries". Palgrave Macmillan.

This publication is a book. Book is available at: http://www.palgrave.com/page/detail/empowering-women-in-work-in-developing-countries-maarten-van-klaveren/?isb=9780230369351


Günther, I. and Y. Schipper (2011a). "Chapter 3: Quantitative Impact Analysis". In: BMZ/ KfW/ IOB (eds.), Impact evaluation of drinking water supply and sanitation programmes. The Hague: IOB



Aulagnier, M, W. Janssens, I. de Beer, G. Van Rooy, E. Gaeb, C. Hesp, J. van der Gaag and T.F. Rinke de Wit (2011), “The Incidence of HIV in Windhoek, Namibia: Demographic and Socio-Economic Associations”, PLoS ONE ¸ 6(10), 1 - 9.


Objective: To estimate HIV incidence and prevalence in Windhoek, Namibia and to analyze socio-economic factors related to HIV infection.

Method: In 2006/7, baseline surveys were performed with 1,753 private households living in the greater Windhoek area; follow-up visits took place in 2008 and 2009. Face-to-face socio-economic questionnaires were administrated by trained interviewers; biomedical markers were collected by nurses; GPS codes of household residences were recorded.

Results: The HIV prevalence in the population (aged.12 years) was 11.8% in 2006/7 and 14.6% in 2009. HIV incidence between 2007 and 2009 was 2.4 per 100 person year (95%CI = 1.9–2.9). HIV incidence and prevalence were higher in female populations. HIV incidence appeared non-associated with any socioeconomic factor, indicating universal risk for the population. For women a positive trend was found between low per-capita consumption and HIV acquisition. A HIV knowledge score was strongly associated with HIV incidence for both men and women. High HIV prevalence and incidence was concentrated in the north-western part of the city, an area with lower HIV knowledge, higher HIV risk perception and lower per-capita consumption.

Discussion: The HIV incidence and prevalence figures do not suggest a declining epidemic in Windhoek. Higher vulnerability of women is recorded, most likely related to economic dependency and increasing transactional sex in Namibia. The lack of relation between HIV incidence and socio-economic factors confirms HIV risks for the overall urban community. Appropriate knowledge is strongly associated to lower HIV incidence and prevalence, underscoring the importance of continuous information and education activities for prevention of infection. Geographical areas were identified that would require prioritized HIV campaigning.

Janssens, W. (2011), “Externalities in program evaluation: The impact of a women’s empowerment program on immunization”, Journal of the European Economic Association, 9(6), 1082 - 1113.


Impact evaluations of development programs usually do not explicitly take into account externalities on non-participants. Based on a unique dataset we estimate the direct as well as the spillover effects of Mahila Samakhya, awomen’s empowerment program in India, on child immunization. The survey covers both participants and non-participants in program villages, as well as respondents in control villages. We account for participation selection bias using instrumental variables. We propose a direct test for the exclusion restriction using the control villages. We find both direct effects on the immunization rates of participants’ children and significant spillovers on immunization rates of non-participants’ children. The impact of interventions might be substantially underestimated if such external effects were not taken into account. Alternative estimation methods such as propensity score matching and a regression discontinuity approach yield comparable results.


Gunning, J.W. (2010), "Risk and savings: a taxonomy", Economics Letters, 107(1), 39 - 41.


The effect of risk on savings depends not just on preferences but also on the type of risk. This helps to explain why the empirical literature reports positive effects for developed countries but negative effects for developing countries.

Gustafsson-Wright, E., W. Janssens and J. van der Gaag (2010), “Low-Cost Health Insurance Schemes to Protect the Poor in Namibia”. In Griffin C., M. Escobar and R. Shaw (Eds.), Impact of Health Insurance in Low- and Middle-Income Countries (pp. 33 - 57). Washington, D.C.: Brookings Institution Press.

This publication is a book chapter in: Griffin C., M. Escobar and R. Shaw (2010). Impact of Health Insurance in Low- and Middle-Income Countries. Washington, D.C.: Brookings Institution Press. Book is available at: http://www.brookings.edu/research/books/2011/theimpactofhealthinsuranceonlowandmiddleincomecountries

Gustafsson-Wright, E.J.E., W. Janssens and J. van der Gaag (2010), "The inequitable impact of health shocks on the uninsured in Namibia", Health Policy and Planning, 26(2), 142 - 156.


The AIDS pandemic in sub-Saharan Africa puts increasing pressure on the buffer capacity of low- and middle-income households without access to health insurance. This paper examines the relationship between health shocks, insurance status and health-seeking behaviour. It also investigates the possible mitigating effects of insurance on income loss and out-of-pocket health expenditure. The study uses a unique dataset based on a random sample of 1769 households and 7343 individuals living in the Greater Windhoek area in Namibia. The survey includes medical testing for HIV infection which allows for the explicit analysis of HIV-related health shocks. We find that the economic consequences of health shocks can be severe for uninsured households even in a country with a relatively well-developed public health care system such as Namibia. The uninsured resort to a variety of coping strategies to deal with the high medical expenses and reductions in income, such as selling assets, taking up credit or receiving financial support from relatives and friends. As HIV-infected individuals increasingly develop AIDS, this will put substantial pressure on the public health care system as well as social support networks. Evidence suggests that private insurance, currently unaffordable to the poor, protects households from the most severe consequences of health shocks.

Janssens, W., I. de Beer, H. Coutinho, G. van Rooy, J. van der Gaag and T. Rinke de Wit (2010), "Estimating HIV prevalence: A cautious note on household surveys in poor settings", British Medical Journal, 341, 1063 - 1063.



W. Janssens (2010). "Womens empowerment and the creation of social capital in Indian villages", World Development, 38, 7, 974 - 988


Community-based development projects are often argued to strengthen social capital. This paper investigates the impact of a women’s empowerment program in India on trust and cooperation, using data on 2,000 households. The program significantly increases trust and stimulates contributions to educational and infrastructural community projects. The effect on informal assistance among households is less consistent. The findings suggest substantial spillovers on the wider community. Households who do not participate in the program themselves but who live in a program village are significantly more trusting and more likely to engage in collective action than households in control villages.

Before 2010

Barron, P., M.P. Kaiser and M.P. Pradhan (2009), "Understanding variations in local conflict: Evidence and implications from Indonesia", World Development, 37(3), 698 - 713.


Recent studies of large-scale ‘‘headline” conflicts have excluded consideration of local conflict, in large part due to the absence of representative data at low levels of geographic specification. This paper is a first attempt to correct for that by assessing the incidence, impacts, and patterns of local conflict in Indonesia. We employ a combination of qualitative fieldwork with an exploratory statistical analysis of the 2003 Village Potential Statistics collected by the Bureau of Statistics (Potensi Desa-PODES), which maps conflict across all of Indonesia’s villages/neighborhoods. Violent conflict can be observed throughout the archipelago. The qualitative analysis shows that local conflicts vary in form and impacts across districts, and that local factors are key. The quantitative analysis, which excludes high conflict areas of Indonesia, confirms the importance of economic factors, with positive correlations between violent conflict and poverty, inequality, and variables measuring economic development. Clustering of ethnic groups and ill-defined property rights were also positively associated with violence.

Beard, V., M. Pradhan, V. Rao, R.S. Cartmill, Rivayani (2008). "Community-driven development and elite capture: Microcredit and community board participation in Indonesia". In V.A. Beard, F. Miraftab and C. Silver (Eds.), Planning and Decentralization: Contested Spaces for Public Action in the Global South (pp. 137 - 157). London: Taylor and Francis.

This publication is a book chapter in: Beard, V.A., F. Miraftab and C. Silver (2008). Planning and Decentralization: Contested Spaces for Public Action in the Global South. London: Taylor and Francis. Book is available at: http://www.tandf.net/books/details/9780415414982/

Elbers, C.T.M., J.W. Gunning and J.J. de Hoop (2009), "Assessing Sector-wide Programs with Statistical Impact Evaluation: A Methodological Proposal", World Development, 37(2), 513 - 520.


Donor agencies, and recipient governments want to assess the effectiveness of aid-supported sector policies. Unfortunately, existing methods for impact evaluation are designed for the evaluation of homogeneous interventions (‘‘projects”) where those with, and without ‘‘treatment” can be compared. The lack of a methodology for evaluations of sector-wide programs is a serious constraint in the debate on aid effectiveness. We propose a method of statistical impact evaluation in situations with heterogeneous interventions, an extension of the double differencing method often used in project evaluations. We illustrate its feasibility with an example from the education sector in Zambia.

Elbers, C.T.M., J.W. Gunning and J.J. de Hoop (2009), "Assessing Sector-wide Programs with Statistical Impact Evaluation: A Methodological Proposal", World Development, 37(2), 513 - 520.


How exposure to risk affects economic growth is a key issue in development. This article quantifies both the ex ante and ex post effects of risk using long-running panel data for rural households in Zimbabwe. It proposes a simulation-based econometric methodology to estimate the structural form of a micro model of household investment decisions under risk. The key finding is that risk substantially reduces growth in
this particular setting: the mean capital stock in the sample is (in expectation) 46 percent lower than in the absence of risk. About two-thirds of the impact of risk is due to the ex ante effect (that is, the behavioral response to risk), which is usually not taken into account in policy design. These results suggest that policy interventions that reduce exposure to shocks or that help households manage risk could be much more effective than is commonly thought. JEL Codes: D10, D91, C51, O12

Elbers, C.T.M., J.W. Gunning and L. Pan (2009), "Insurance and Rural Welfare: What Can Panel Data Tell Us?", Applied Economics, 41(24), 3093 - 3101.


Assessing the scope for insurance in rural communities usually requires a structural model of household behaviour under risk. One of the few empirical applications of such models is the study by Rosenzweig and
Wolpin (1993) who conclude that Indian farmers in the ICRISAT villages would not benefit from the introduction of formal weather insurance. In this article we investigate how models such as theirs can be estimated from panel data on production and assets. We show that if assets can take only a limited number of values the coefficients of the model cannot be estimated with reasonable precision. We also show that this can affect the conclusion that insurance would not be welfare improving.

Elbers, C.T.M., P.F. Lanjouw, J. Mistiaen and B. Ozler (2008), "Reinterpreting between-group inequality", Journal of Development Economics, 6(3), 231 - 245.


We evaluate observed inequality between population groups against a benchmark of the maximum between-group inequality attainable given the number and relative sizes of those groups under examination. Because our measure is normalized by these parameters, drawing comparisons across different settings is less problematic than with conventional inequality decompositions. Moreover, our measure can decline with finer sub-partitioning of population groups. Consequently, the exact manner in which one groups the population acquires greater significance. Survey data from various countries suggest that our approach can provide a complementary perspective on the question of whether (and how much) a particular population breakdown is salient to an assessment of inequality in a country.

Gunning, J.W. (2008), "Het Nederlandse Afrikabeleid 1998-2006", Internationale Spectator, 62, 304 - 307.



Gustafsson-Wright, E.J.E., A. Asfaw and J. van der Gaag (2009), "Willingness to Pay for Health Insurance: An Analysis of the Potential Market for New Low-Cost Health Insurance in Namibia", Social Science and Medicine, 69, 1351 - 1359.


This study analyzes the willingness to pay for health insurance and hence the potential market for new low-cost health insurance product in Namibia, using the double bounded contingent valuation (DBCV) method. The findings suggest that 87 percent of the uninsured respondents are willing to join the proposed health insurance scheme and on average are willing to insure 3.2 individuals (around 90 percent of the average family size). On average respondents are willing to pay NAD 48 per capita per month and respondents in the poorest income quintile are willing to pay up to 11.4 percent of their income. This implies that private voluntary health insurance schemes, in addition to the potential for protecting the poor against the negative financial shock of illness, may be able to serve as a reliable income flow for health care providers in this setting.

Janssens, W., E.J.E. Gustafsson-Wright, I. de Beer and J. van der Gaag (2008), "A Unique Low-Cost Private Health Insurance Program in Namibia: Protection from Health Shocks Including HIV/AIDS", Development Issues, 10(2), 13 - 15.



Oostendorp, R. (2009), "Globalization and the Gender Wage Gap", World Bank Economic Review, 23(1), 141 - 161.


There are several theoretical reasons why globalization will have a narrowing as well as a widening effect on the gender wage gap, but little is known about the actual impact, except for some country studies. This study contributes to the literature in three respects. First, it is a large cross-country study of the impact of globalization on the gender wage gap. Second, it employs the rarely used ILO October Inquiry database, which is the most far-ranging survey of wages around the world. Third, it focuses on the within-occupation gender wage gap, an alternative to the commonly used raw and residual wage gaps as a measure of the gender wage gap. This study finds that the occupational gender wage gap tends to decrease with increasing economic development, at least in richer countries, and to decrease with trade and foreign direct investment (FDI) in richer countries, but finds little evidence that trade and FDI also reduce the occupational gender wage gap in poorer countries.

Oostendorp, R., T. Q. Trung and N.T. Tung (2009), "The Changing Role of Non-Farm Household Enterprises in Vietnam", World Development, 37(3), 632 - 644.


In this paper we study the importance of the non-farm household enterprise (NFHE) sector in Vietnam. We do find that NFHEs increase income and reduce between-household inequality. However, the role of the NFHE sector has been diminishing, especially in urban areas, and the NFHEs have been affected by trade liberalization in the period 1993–2002. In terms of policy, this suggests that there is increasing scope for targeting NFHE sector policies at those NFHEs that are in the best position to benefit from the new opportunities in the liberalizing environment.

Pradhan, M. P. (2009), "Welfare analysis with a proxy consumption measure: Evidence from a repeated experiment in Indonesia", Fiscal Studies, 30(3), 391 - 417.


Every three years, Indonesia fields simultaneously two nationwide surveys which collect consumption data. One collects consumption using 23 questions, the other using 320 questions. Based on a repeated experiment in which the two questionnaires were randomly assigned across households, this paper examines the consequences of using a higher level of aggregation in questioning. A mapping of distribution functions reveals the combined effect of systematic differences in measurement and measurement error. Comparing means by subgroups, the effect of additive measurement error is eliminated, and it is found that using a higher level of aggregation yields a lower consumption measure and that the fraction of underestimation increases as consumption rises. A 1 per cent increase in average consumption increases the fraction by which consumption is underestimated by about 0.4 percentage points. Next, the paper examines the consequences of using the short consumption questionnaire in welfare analysis. Higher relative measurement error in the consumption measure derived from the short questionnaire results in higher poverty estimates even if the poverty line is adjusted to take account of the systematic underestimation. Small differences are found for analysis that is based on the rank the individual holds in the consumption distribution. In gradient analysis, it seems impossible to devise a simple correction factor for the higher consumption elasticities that follow when the short questionnaire is used.

Pradhan, M.P., F. Saadah and R.A. Sparrow (2007), "Did the Health Card Ensure Access to Medical Care for the Poor during Indonesia


The Indonesian Social Safety Net health card program was implemented in response to the economic crisis that hit Indonesia in 1997, to preserve access to health care services for the poor. Health cards were allocated to poor households, entitling them to subsidized care from public health care providers. The providers received budgetary support to compensate for the extra demand. This article focuses on the effect of the
program on primary outpatient health care use, disentangling the direct effect of allocating health cards from the indirect effect of government transfers to health care facilities. For poor health card owners the program resulted in a net increase in use of outpatient care, while for nonpoor health card owners the program resulted mainly in a substitution from private to public health care. The largest effect of the program seems to have come from a general increase in the supply of public services resulting from the budgetary support to public providers. These benefits seem to have been captured mainly by the nonpoor. As a result, most of the benefits of the health card program went to the nonpoor, even though distribution of the health cards was pro poor. The results suggest that had the program, in addition to targeting the poor, established a closer link between provision of services to the target groups and funding, the overall results would have been more propoor. JEL codes: H51, I11, I38.