M-quantile models with application to poverty mapping

Over the last decade there has been growing demand for estimates of population characteristics at small area level. Unfortunately, cost constraints in the design of sample surveys lead to small sample sizes within these areas and as a result direct estimation, using only the survey data, is inappropriate since it yields estimates with unacceptable levels of precision. Small area models are designed to tackle the small sample size problem. The most popular class of models for small area estimation is random effects models that include random area effects to account for between area variations. However, such models also depend on strong distributional assumptions, require a formal specification of the random part of the model and do not easily allow for outlier robust inference. An alternative approach to small area estimation that is based on the use of M-quantile models was recently proposed by Chambers and Tzavidis (Biometrika 93(2):255–268, 2006) and Tzavidis and Chambers (Robust prediction of small area means and distributions. Working paper, 2007). Unlike traditional random effects models, M-quantile models do not depend on strong distributional assumption and automatically provide outlier robust inference. In this paper we illustrate for the first time how M-quantile models can be practically employed for deriving small area estimates of poverty and inequality. The methodology we propose improves the traditional poverty mapping methods in the following ways: (a) it enables the estimation of the distribution function of the study variable within the small area of interest both under an M-quantile and a random effects model, (b) it provides analytical, instead of empirical, estimation of the mean squared error of the M-quantile small area mean estimates and (c) it employs a robust to outliers estimation method. The methodology is applied to data from the 2002 Living Standards Measurement Survey (LSMS) in Albania for estimating (a) district level estimates of the incidence of poverty in Albania, (b) district level inequality measures and (c) the distribution function of household per-capita consumption expenditure in each district. Small area estimates of poverty and inequality show that the poorest Albanian districts are in the mountainous regions (north and north east) with the wealthiest districts, which are also linked with high levels of inequality, in the coastal (south west) and southern part of country. We discuss the practical advantages of our methodology and note the consistency of our results with results from previous studies. We further demonstrate the usefulness of the M-quantile estimation framework through design-based simulations based on two realistic survey data sets containing small area information and show that the M-quantile approach may be preferable when the aim is to estimate the small area distribution function.     

Retrospective information on health status and its application for population health measures

Healthy life expectancies are almost always calculated by using health data from cross-sectional surveys. This type of calculation is done partly because data from longitudinal surveys are not always available, and when they are available, they are collected at intervals that are longer than one year. In such cases, collecting health information retrospectively for the years skipped by the survey is useful. The main purpose of this paper is to show how retrospective health information can be used to estimate life expectancies in different health states. Healthy life expectancies are estimated with and without using data on retrospective health information, and the corresponding estimates are compared. The two sets of estimates are similar. We conclude that retrospectively assessed health information based on a one-year recall period can be used to estimate years of life in various health states and that estimates based on such information will closely approximate estimates based on concurrent health information.     

Moving and union dissolution

This paper examines the effect of migration and residential mobility on union dissolution among married and cohabiting couples. Moving is a stressful life event, and a large, multidisciplinary literature has shown that family migration often benefits one partner (usually the man) more than the other Even so, no study to date has examined the possible impact of within-nation geographical mobility on union dissolution. We base our longitudinal analysis on retrospective event-history data from Austria. Our results show that couples who move frequently have a significantly higher risk of union dissolution, and we suggest a variety of mechanisms that may explain this.     

Risk preferences and the timing of marriage and childbearing

The existing literature on marriage and fertility decisions pays little attention to the roles played by risk preferences and uncertainty. However given uncertainty regarding the availability of suitable marriage partners, the ability to contracept, and the ability to conceive, women's risk preferences might be expected to play an important role in marriage and fertility timing decisions. By using data from the Panel Study of Income Dynamics (PSID), I find that measured risk preferences have a significant effect on the timing of both marriage and fertility. Highly risk-tolerant women are more likely to delay marriage, consistent with either a search model of marriage or a risk-pooling explanation. In addition, risk preferences affect fertility timing in a way that differs by marital status and education, and that varies over the life cycle. Greater tolerance for risk leads to earlier births at young ages, consistent with these women being less likely to contracept effectively. In addition, as the subgroup of college-educated, unmarried women nears the end of their fertile periods, highly risk-tolerant women are likely to delay childbearing relative to their more risk-averse counterparts and are therefore less likely to become mothers. These findings may have broader implications for both individual and societal well-being.     

Coparenting and nonresident fathers’ involvement with young children after a nonmarital birth

We use data from the Fragile Families and Child Wellbeing Study to investigate the association between coparenting quality and nonresident fathers' involvement with children over the first five years after a nonmarital birth. We find that about one year after a nonmarital birth, 48% of fathers are living away from their child, rising to 56% and then to 63% at three and five years, respectively Using structural equation models to estimate cross-lagged effects, we find that positive coparenting is a strong predictor of nonresident fathers' future involvement, whereas fathers' involvement is only a weak (but significant) predictor of future coparenting quality. The positive effect of coparenting quality on fathers' involvement is robust across several techniques designed to address unobserved heterogeneity and across different strategies for handling missing data. We conclude that parents' ability to work together in rearing their common child across households helps keep nonresident fathers connected to their children and that programs aimed at improving parents' ability to communicate may have benefits for children irrespective of whether the parents' romantic relationship remains intact.     

Changing educational inequalities in india in the context of affirmative action

Indian society suffers from substantial inequalities in education, employment, and income based on caste and ethnicity. Compensatory or positive discrimination policies reserve 15% of the seats in institutions of higher education and state and central government jobs for people of the lowest caste, the Scheduled Caste; 7.5% of the seats are reserved for the Scheduled Tribe. These programs have been strengthened by improved enforcement and increased funding in the 1990s. This positive discrimination has also generated popular backlash and on-the-ground sabotage of the programs. This paper examines the changes in educational attainment between various social groups for a period of nearly 20 years to see whether educational inequalities have declined over time. We use data from a large national sample survey of over 100,000 households for each of the four survey years--1983, 1987-1988, 1993-1994, and 1999-2000--and focus on the educational attainment of children and young adults aged 6-29. Our results show a declining gap between dalits, adivasis, and others in the odds of completing primary school. Such improvement is not seen for Muslims, a minority group that does not benefit from affirmative action. We find little improvement in inequality at the college level. Further, we do not find evidence that upper-income groups, the so-called creamy layer of dalits and adivasis, disproportionately benefit from the affirmative action programs at the expense of their lower-income counterparts.     

Demographic Differentials and Demographic Integration of Turkish and Kurdish Populations in Turkey

The objectives of the study are threefold: (1) to provide estimates of the total populations and spatial distributions of different language groups in Turkey, (2) to test whether the commonly held belief that Turkish-speaking and Kurdish-speaking populations are “actors” of different demographic regimes is true, and (3) to assess whether a process of integration, in the form of intermarriage of Turks and Kurds is under way in Turkey. Data come mainly from the 2003 Turkish Demographic and Health Survey (TDHS-2003). Based on the assumption that the mother tongue composition of women is also representative of that of the whole population, the results of the TDHS-2003 imply that of the population of Turkey, 83% are Turkish-speaking, 14% are Kurdish-speaking, 2% are Arabic-speaking and the remaining 1% belong to other language groups. Results show that despite intensive internal migration movements in the last 50 years, strong demographic differentials exist between Turkish and Kurdish-speaking populations, and that the convergence of the two groups does not appear to be a process under way. Turks and Kurds do indeed appear to be actors of different demographic regimes, at different stages of demographic and health transition processes.     

Social vulnerability and migration in the wake of disaster: the case of Hurricanes Katrina and Rita

This study explores the relationship between place-based social vulnerability and post-disaster migration in the U.S. Gulf Coast region following Hurricanes Katrina and Rita. Using county-level data from the U.S. Census Bureau, we develop a regional index of social vulnerability and examine how its various dimensions are related to migration patterns in the wake of the storms. Our results show that places characterized by greater proportions of disadvantaged populations, housing damage, and, to a lesser degree, more densely built environments were significantly more likely to experience outmigration following the hurricanes. Our results also show that these relationships were not spatially random, but rather exhibited significant geographic clustering. We conclude with a discussion of the implications of these findings for future research and public policy.     

The Influence of Acculturation on Breastfeeding Initiation and Duration for Mexican-Americans

This paper uses data from the Fragile Families and Child Wellbeing Study to test the hypotheses that (1) similar to other positive pre- and post-natal outcomes, Mexican immigrant mothers are more likely to breastfeed, and to breastfeed longer, than white or Mexican-American mothers; and (2) acculturation accounts for the ethnic/nativity differential in breastfeeding initiation and duration. The results support both hypotheses. Mexican immigrants to the U.S. are much more likely than whites to breastfeed, and to breastfeed longer. Mexican-American mothers, after controlling for background characteristics, have similar initiation and duration to whites. Using expanded acculturation measures developed for this paper, acculturation accounts for some of the difference between whites and Mexican immigrants in breastfeeding initiation, and much of the difference for breastfeeding duration. The results suggest that low levels of acculturation operate to protect Mexican immigrants from choosing to formula-feed, which gives their babies many health advantages, and may be associated with better health outcomes across the life course. The results also suggest that successive generations of Mexican immigrants may abandon breastfeeding, which is deleterious for their infants.     

Technological innovation and inequality in health

The effect of education on health has been increasing over the past several decades. We hypothesize that this increasing disparity is related to health-related technical progress: more-educated people are the first to take advantage of technological advances that improve health. We test this hypothesis using data on disease-specific mortality rates for 1980 and 1990, and cancer registry data for 1973–1993. We estimate education gradients in mortality using compulsory schooling as a measure of education. We then relate these gradients to two measures of health-related innovation: the number of active drug ingredients available to treat a disease, and the rate of change in mortality from that disease. We find that more-educated individuals have a greater survival advantage in those diseases for which there has been more health-related technological progress.