Showing papers by "Duncan Thomas published in 1996"

Education Across Generations in South Africa

Abstract: Racially segregated education was a central pillar propping up the apartheid system in South Africa. The 1953 Bantu Education Act centralized control of black education and linked tax receipts from black to public expenditure on their education. In 1975, expenditure on the average white was more than 15 times larger than that on the average black student.

Education across Generations in South Africa

Abstract: Racially segregated education was a central pillar propping up the apartheid system in South Africa. The 1953 Bantu Education Act centralized control of black education and linked tax receipts from black to public expenditure on their education. In 1975, expenditure on the average white was more than 15 times larger than that on the average black student.(This abstract was borrowed from another version of this item.)

Fertility, Education and Resources in South Africa

Abstract: Population and education are likely to play a central role in public policy in South Africa as it emerges form years of apartheid. Using household survey data, collected as part of the Project for Statistics on Living Standards and Development, the paper examine some of the mechanisms that underlie the negative association between fertility and education.

Fertility, Contraceptive Choice, and Public Policy in Zimbabwe

Abstract: Zimbabwe has invested massively in public infrastructure since independence in 1980. The impact of these investments on demographic outcomes is examined using household survey data matched with two community level surveys.

Measurement and mismeasurement of social indicators

Abstract: Measurement of social indicators is not without its pitfalls, however, and drawing conclusions based on comparisons of national aggregates is fraught with difficulties, especially when data sources are sketchy. The paper in that issue make a compelling argument for investing in improving the quality - and frequency - of data-collection efforts. However, even when "good" survey data do exist, serious and often quite subtle issues of comparability and measurmenet still abound.

Fertility, contraceptive choice, and public policy in Zimbabwe

Abstract: Zimbabwe has invested massively in public infrastructure since independence in 1980. The impact of these investments on demographic outcomes is examined using household survey data matched with two community level surveys. A woman's education is a powerful predictor of both fertility and contraceptive use. These relationships are far from linear and have changed shape in recent years. After controlling for household resources, both the availability and quality of health and family planning services have an important impact on the adoption of modern contraceptives. In particular, outreach programs such as mobile family planning clinics and community- based distributors (CBDs) have been especially successful. However, not all women are equally served by this infrastructure. For example, CBDs have a bigger impact on younger, better educated women, while mobile family planning clinics appear to have more success with older, less educated women.

Measurement and Mismeasurement of Social Indicators

Abstract: Measurement of social indicators is not without its pitfalls, however, and drawing conclusions based on comparisons of national aggregates is fraught with difficulties, especially when data sources are sketchy. The paper in that issue make a compelling argument for investing in improving the quality - and frequency - of data-collection efforts. However, even when "good" survey data do exist, serious and often quite subtle issues of comparability and measurmenet still abound. (This abstract was borrowed from another version of this item.)

Quality of Health Care, Survivial and Health Outcomes in Ghana

Abstract: This paper analyzes the effect of quality and accessibility of health services and other public infrastructure on the health of children in Ghana. We focus on child survival, child height and weight using data from the Ghana Living Standards Survey. The results suggest an important role for public health policy in eliminating the rural-urban disparities in health status and particularly in improving the health status of rural children and reducing their mortality rates.

Parental Investments in Schooling: The Roles of Gender and Resources in Urban Brazil

Abstract: In this study data from a large household labor force survey conducted in Brazil in 1982 (which had a special supplement focused on education) were analyzed in order to: 1) compare the impact of maternal and paternal education on child educational attainment 2) compare the impact of parental education on males and females 3) discover the "differences-in-differences" in the impact of each parents education on sons relative to daughters and 4) examine the "differences-in-differences" effects in order to test the hypothesis that parents do not behave as if they pool their incomes. This report contains a description of the underlying empirical strategy the data and the rapidly increasing trends in completed education of men and women in Brazil during the past 50 years (especially among women). The discussion of regression results includes a clarification of how samples are constructed as well as a description of the specification of the empirical model. After documenting the relative importance of maternal and paternal education (the effect of mothers schooling is substantially and significantly greater than that of fathers schooling) it is shown that the effects of parental education differ between sons and daughters with maternal education having a bigger impact on daughters relative to sons and vice versa for fathers. The data also support the hypothesis that mothers and fathers incomes have different effects on the education of boys and girls (paternal income having more effect on the education of a son relative to a daughter and vice versa). This indicates that parents do not pool their incomes. As the education of females relative to males continues to rise in Brazil the educational attainment of children (especially daughters) will continue to increase rapidly.

Does Head Start Help Hispanic Children

Abstract: Poor educational attainment is a persistent problem among latino children, relative to non-Latinos. This paper examines the effects of participation in the Head Start program on Latinos. We find that large and significat benefits accrue to Head Start children when we compare them to siblings who did not participate in the program.

Does Head Start Help Hispanic Children

Abstract: Poor educational attainment is a persistent problem among Latino children, relative to non-Latinos. This paper examines the effects of participation in the Head Start program on Latinos. We find that large and significant benefits accrue to Head Start children when we compare them to siblings who did not participate in the program. On average, Head Start closes at least 1/4 of the gap in test scores between Latino children and non-Hispanic white children, and 2/3 of the gap in the probability of grade repetition. Latinos are not a homogenous group and we find that the benefits of Head Start are not evenly distributed across sub-groups. Relative to siblings who attend no preschool from Head Start are greatest among children of Mexican-origin and children of native-born mothers, especially those whose mothers have more human capital. In contrast, Latino children whose mothers are foreign-born and Puerto Rican children appear to reap little benefit from attending Head Start, relative to their siblings.

Head Start and Cognition Among Latino Children

Abstract: Poor educational attainment relative to non-Latinos is a persistent problem for Latino children. This paper examines the capacity of the Head Start program to affect test scores and schooling achievement among these children. Large positive effects are found on all the measures we examine. On average, Head Start closes 1/3 of the gap in test scores between Latino children and non-Hispanic white children, and 2/3 of the gap in the probability of grade repetition. However, these effects are not evenly distributed across groups or regions. In particular, while the gains to second (and higher) generation children are relatively uniform across the country, first-generation children outside California do not appear to gain from enrollment in the program. Conversely, first-generation children in California reap gains in test scores that are twice as large as those we find for all Latino children. This result suggests that early intervention programs that are tailored to the needs of specific groups can be very effective.

Response to “Evolution of Epidemiologic Evidence on Magnetic Fields and Childhood Cancers”

Abstract: Dr. Poole has made a number of useful points about the interpretation of studies of the association of childhood cancers with extremely low frequency magnetic fields (1). We wish to comment on only two of his points. First, Dr. Poole takes issue with the appliance-specific relative risks that were reported in the two papers in this issue (2, 3) and several earlier ones, including another Los Angeles study (4). We agree with his desire for an exposure assessment that consolidates appliances with other sources of magnetic fields, including power lines. However, numerous difficulties preclude doing so at this time. Too little is known about the fields generated by each appliance at the target organs, variations between brands, duration and frequency of use, and other modifying influences needed for a sensible summary index. More important is the uncertainty over the appropriate "exposure metric," a single number that represents a subject's magnetic field environment, including its frequency spectrum, time variation, polarization, spatial orientation, and high-frequency transients. Since fields from appliances and power lines differ in many of these qualities, weighting exposures from various electromagnetic field sources requires an exposure metric that is hypothetically carcinogenic. "Combining apples and oranges" makes sense in dietary epidemiology only because fructose has been identified as an etiologically relevant nutrient! Although summary electromagnetic field exposure indices would be useful, their development clearly poses formidable challenges to epidemiologists, exposure assessors, and biologists. During the present state of ignorance, however, we feel that appliance-specific risk estimates may provide potential clues about etiologically important components of magnetic fields (if any) and may provide some preliminary guidance to individuals and officials in making decisions about their safety. Second, we agree that the best use of household magnetic field measurements is not as a direct cancer risk factor, but in building exposure models from wiring configuration data. Where Dr. Poole uses the measured fields simply to combine categories of the Wertheimer-Leeper wire code (5), we feel that a more powerful application is predicting long-term residential exposures to a variety of magnetic field metrics. For example, we recently developed a regression model for predicting the mean magnetic field from measurements, wire configurations, and physical principles (6). When applied to the data from the Los Angeles childhood leukemia study (3), this model predicted household magnetic fields far better than did the Wertheimer-Leeper code and was significantly associated with leukemia risk, providing new evidence for magnetic field carcinogenicity. However, the predicted fields did not improve upon the Wertheimer-Leeper code in a multivariate risk model, suggesting that the mean magnetic field may not be the appropriate exposure metric (6). Such wire configuration models could be used to evaluate other plausible exposure metrics. Metrics correlated with the Wertheimer-Leeper categories would more likely be associated with cancer. We have identified two such candidates: the field's autocorrelation over time (7) and frequency components that create ionic resonances with the earth's magnetic field (8). We are looking forward to the postpublication phase of the peer-review process that Dr. Poole describes. We hope Dr. Poole's commentary (1) and the responses by Gurney et al. (9) and ourselves to this debate will stimulate further thinking about some of these methodological issues, as well as our substantive conclusions.