The Virgin HIV Puzzle: Can Misreporting Account for the High Proportion of HIV Cases in Self-Reported Virgins?

It is widely believed that HIV is predominantly sexually transmitted in Sub Saharan Africa. This claim which is inconsistent with national representative data from Lesotho, Zimbabwe, and Swaziland, which reveals that a significant proportion of HIV infections occurred in adolescents who claim to be virgins. Two explanations for this observation have been proposed: adolescents misreport sexual status or non-sexual risks are more prevalent than previously asserted. This paper empirically uncovers the implicit assumptions underlying this discussion, by estimating the proportion of sexually transmitted HIV infections assuming that misreporting is irrelevant, and the proportion of misreporting necessary to conclude that HIV is predominantly sexually transmitted. It shows that under the no-misreporting assumption, 70% of HIV cases in the respective sample of unmarried adolescent women is not due to sexual transmission. The assumption that HIV is predominantly sexually transmitted is only valid, if more than 55% of unmarried adolescent women who are sexually active have misreported sexual activity status. This research is designed to gain better understanding on the importance of different transmission modes. This is important to design combination prevention to achieve maximum impact on HIV prevention.Population attributable fraction; non-classical measurement error; HIV transmission mode

The Virgin HIV Puzzle: Can misreporting account for the high proportion of HIV cases in self-reported virgins?

The Demographic and Health Surveys from Lesotho, Zimbabwe, and Malawi reveal that a significant proportion of HIV infections in adolescent women occurred in women who claim to be virgin. Two possible conclusions arise from this observation: adolescent women misreport sexual status or non-sexual risk is more relevant than previously asserted. This paper uses a nonparametric model to estimate the proportion of HIV infections associated with sexual activity under different assumptions on data accuracy. It shows that there is an inverse relation between data accuracy and importance of sexual HIV transmission. If all adolescent women in the considered sub-sample correctly report sexual activity, 70% of HIV infections cannot be attributed to sexual HIV transmission. The model predicts that more than 95% of HIV infections are due to sexual HIV infections, if a substantial proportion of self-reported virgins (between 40 and 90%) misreport sexual status. --adolescent,HIV,misreporting,nonparametric modelling,sexual transmission

Evaluating Nationwide Health Interventions When Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behavior on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi's main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi's ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.health intervention, semi-parametric estimation, treatment effect

Evaluating Nationwide Health Interventions When Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behavior on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi's main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi's ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.Treatment effect; semi-parametric estimation; health intervention

Evaluating Nationwide Health Interventions when Standard Before-After Doesn't Work: Malawi's ITN Distribution Program

Nationwide health interventions are difficult to evaluate as contemporaneous control groups do not exist and before-after approaches are usually infeasible. We propose an alternative semi-parametric estimator that is based on the assumption that the intervention has no direct effect on the health outcome but influences the outcome only through its effect on individual behavior. We show that in this case the evaluation problem can be divided into two parts: (i) the effect of the intervention on behavior, for which a conditional before-after assumption is more plausible; and (ii) the effect of the behaviour on the health outcome, where we exploit that a contemporaneous control groups exists for behavior. The proposed estimator is used to evaluate one of Malawi’s main malaria prevention campaigns, a nationwide insecticide-treated-net (ITN) distribution scheme, in terms of its effect on infant mortality. We exploit that the program affects child mortality only via bed net usage. We find that Malawi’s ITN distribution campaign reduced child mortality by 1 percentage point, which corresponds to about 30% of the total reduction in infant mortality over the study period.treatment effect, semi-parametric estimation, health intervention

The tempest: Using a natural disaster to evaluate the link between wealth and child development

How does family wealth affect children's development in the short- and long-run? We address this question by exploiting a shock occurred to family’s real estate, i.e. housing damages caused by a super typhoon. Our identification strategy is based on a comparison of children, who all lived in the same local area and thus were confronted with the same macro-economic shock, but only some experienced housing damages. We present evidence in favor of housing damages being essentially a severe wealth shock, with no effects on other observable channels which might directly harm children’s development. The shock results in a decline of educa-tional investments, but not of health-related investments. We observe a deterioration of chil-dren’s educational achievements in the short-run and even more pronounced in the long-run. Our findings are mainly driven by children whose families are at the bottom of the wealth distribution or lack the support of a strong family network.Child development, wealth effects, natural disaster

A cautionary tale about control variables in IV estimation

Many instrumental variable (IV) regressions include control variables to justify (conditional) independence of the instrument and the potential outcomes. The plausibility of conditional IV independence crucially depends on the timing when the control variables are determined. This paper systemically works through different IV models and discusses the (conditions for the) satisfaction of conditional IV independence when controlling for covariates measured (a) prior to the instrument, (b) after the treatment, or (c) both. To illustrate these identification issues, we consider an empirical application using the Vietnam War draft risk as instrument either for veteran status or education to estimate the effects of these variables on labor market and health outcomes

Would you train me with my mental illness? Evidence from a discrete choice experiment

The low employment among people with disabilities in general, and mental disorders in particular, generates high costs to the society. This raises the need to develop effective vocational rehabilitation methods. Supported Education/Employment is effective in increasing sustainable employment for people with mental disorders. This vocational rehabilitation method places patients directly in realistic work settings instead of training them in a protected work environment. Supported Education and Employment has not yet been widely implemented. Using a discrete choice experiment, we demonstrate that one of the key problems is to find employers willing to provide training. Non-cognitive dysfunctions are the main deterrents.upported Vocational Education & Training; vocational rehabilitation; mental disorders; discrete choice experiment

Direct and indirect effects based on difference-in-differences with an application to political preferences following the Vietnam draft lottery

This paper proposes a difference-in-differences approach for disentangling a total treatment effect on some outcome into a direct effect as well as an indirect effect operating through a binary intermediate variable – or mediator – within strata defined upon how the mediator reacts to the treatment. Imposing random treatment assignment along with specific common trend (and further) assumptions identifies the direct effects on the always and never takers, whose mediator is not affected by the treatment, as well as the direct and indirect effects on the compliers, whose mediator reacts to the treatment. We provide an empirical application based on the Vietnam draft lottery, where we analyse the impact of the random draft lottery number on political preferences. The results suggest that a high draft risk due to the lottery leads to a relative increase in mild preferences for the Republican Party, but has no effect on strong preferences for either party or on policy contents. Moreover, the increase in Republican support is mostly driven by the direct effect