How can we measure the causal effects of social networks using observational data? Evidence from the diffusion of family planning and AIDS worries in South Nyanza District, Kenya

This study presents estimates that social networks exert causal and substantial influences on individuals’ attitudes and behaviors. The study explicitly allows for the possibility that social networks are not chosen randomly, but rather that important characteristics such as unobserved preferences and unobserved community characteristics determine not only the outcomes of interest but also the informal conversational networks in which they are discussed. Longitudinal survey data from rural Kenya on family-planning and AIDS are used to estimate the impact of social networks while controlling for their unobserved determinants. There are four major findings: First, the endogeneity of social networks can substantially distort the usual cross-sectional estimates of network influences. Second, social networks have significant and substantial effects even after controlling for unobserved factors that may determine the nature of the social networks. Third, these network effects generally are nonlinear and asymmetric. In particular, they are relatively large for individuals who have at least one network partner who is perceived to be using contraceptives or or to be at high risk of HIV/AIDS, which is consistent with S-shaped diffusion models that have been emphasized in the literature. Fourth, the effects of networks are not confined to the use of family planning by women, the focus of much of the literature on networks in demography, but appear to be more general, influencing responses to HIV/AIDS, and influencing men as well as women. (AUTHORS)

Quality of life and perceived health status in adults with congenitally corrected transposition of the great arteries

ObjectiveThe purpose of this study is to assess perceived health status and quality of life in adults with congenitally corrected transposition of the great arteries who have not undergone anatomic repair.MethodsQuality of life as measured by the satisfaction with life scale and linear analog scales and perceived health status as measured by the Short Form 36 Health Survey (version 1) were evaluated in 25 adults with congenitally corrected transposition and compared with a control group of 25 adults with mild, hemodynamically insignificant defects.ResultsInstruments were returned by 83% of patients (25/30; 11 male; mean age, 44.6 ± 16 years). Health status by the linear analog scale was significantly lower (P = .03) in subjects (median, 80; range, 15–100) than in controls (median, 85; range, 65–100). Quality of life by the satisfaction with life scale was also lower (P = .009) in subjects (mean, 24 ± 8) compared with controls. Age was negatively correlated with the Short Form 36 Health Survey physical functioning (r = −0.41, P = .04), bodily pain (r = −0.5, P = .01), and physical component (r = −0.56, P = .004) summary scores in adults with congenitally corrected transposition but not in controls.ConclusionsAdults with congenitally corrected transposition have lower reported health status and satisfaction with life than a control population, with perceived health status declining with advancing age

Art

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Attrition in longitudinal household survey data

Longitudinal household data can have considerable advantages over much more widely used cross-sectional data. The collection of longitudinal data, however, may be difficult and expensive. One problem that has concerned many analysts is that sample attrition may make the interpretation of estimates problematic. Such attrition may be particularly severe in areas where there is considerable mobility because of migration between rural and urban areas. Many analysts share the intuition that attrition is likely to be selective on characteristics such as schooling and that high attrition is likely to bias estimates made from longitudinal data. This paper considers the extent of and implications of attrition for three longitudinal household surveys from Bolivia, Kenya, and South Africa that report very high per-year attrition rates between survey rounds. Our estimates indicate that (1) the means for a number of critical outcome and family background variables differ significantly between attritors and nonattritors; (2) a number of family background variables are significant predictors of attrition; but (3) nevertheless, the coefficient estimates for “standard” family background variables in regressions and probit equations for the majority of the outcome variables considered in all three data sets are not affected significantly by attrition. Therefore, attrition apparently is not a general problem for obtaining consistent estimates of the coefficients of interest for most of these outcomes. These results, which are very similar to results for developed economies, suggest that for these outcome variables—despite suggestions of systematic attrition from univariate comparisons between attritors and nonattritors, multivariate estimates of behavioral relations of interest may not be biased due to attrition.Household surveys Methodology ,

Attrition in longitudinal household survey data

Longitudinal household data can have considerable advantages over much more widely used cross-sectional data. The collection of longitudinal data, however, may be difficult and expensive. One problem that has concerned many analysts is that sample attrition may make the interpretation of estimates problematic. Such attrition may be particularly severe in areas where there is considerable mobility because of migration between rural and urban areas. Many analysts share the intuition that attrition is likely to be selective on characteristics such as schooling and that high attrition is likely to bias estimates made from longitudinal data. This paper considers the extent of and implications of attrition for three longitudinal household surveys from Bolivia, Kenya, and South Africa that report very high per-year attrition rates between survey rounds. Our estimates indicate that (1) the means for a number of critical outcome and family background variables differ significantly between attritors and nonattritors; (2) a number of family background variables are significant predictors of attrition; but (3) nevertheless, the coefficient estimates for “standard” family background variables in regressions and probit equations for the majority of the outcome variables considered in all three data sets are not affected significantly by attrition. Therefore, attrition apparently is not a general problem for obtaining consistent estimates of the coefficients of interest for most of these outcomes. These results, which are very similar to results for developed economies, suggest that for these outcome variables—despite suggestions of systematic attrition from univariate comparisons between attritors and nonattritors, multivariate estimates of behavioral relations of interest may not be biased due to attrition.Household surveys Methodology ,

Oxidation and formation of deposit precursors in hydrocarbon fuels

The oxidation of two jet turbine fuels and some pure hydrocarbons was studied at 130 C with and without the presence of small amounts of N-methyl pyrrole (NMP) or indene. Tendency to form solid-deposit precursors was studied by measuring soluble gum formation as well as dimer and trimer formation using field ionization mass spectrometry. Pure n-dodecane oxidized fastest and gave the smallest amount of procursors. An unstable fuel oil oxidized much slower but formed large amounts of precursors. Stable Jet A fuel oxidized slowest and gave little precursors. Indene either retarded or accelerated the oxidation of n-dodecane, depending on its concentration, but always caused more gum formation. The NMP greatly retarded n-dodecane oxidation but accelerated Jet A oxidation and greatly increased the latter's gum formation. In general, the additive reacted faster and formed most of the gum. Results are interpreted in terms of classical cooxidation theory. The effect of oxygen pressure on gum formation is also reported

Childhood health-care practices among Italians and Jews in the United States, 1910-1940

This paper examines attitudes toward childhood health-care practices among urban Italian and Jewish families in the United States in the first part of the twentieth century. Although women in both groups were concerned about their children’s health, Italian and Jewish respondents differed in their attitudes toward home remedies, doctors, and medical advice literature. Jewish women were more likely to turn rapidly to professional medical assistance, typically from Jewish doctors, whereas Italian women were more likely to rely longer on common sense before eventually seeking professional medical intervention outside the family and ethnic group. These differences are evident both in the respondents’ recollections of their mothers’ and their own child-care practices, and suggest persistent ethnic cultures. That differences in child care are consistent with the mortality differences documented in other sources supports previous speculations about the importance of child care, and thus the role of culture in health transitions

Attrition in longitudinal household survey data - some tests for three developing-country samples

For capturing dynamic demographic relationships, longitudinal household data can have considerable advantages over more widely used cross-sectional data. But because the collection of longitudinal data may be difficult and expensive, analysts must assess the magnitudes of the problems, specific to longitudinal, but not to cross-sectional data. One problem that concerns many analysts is that sample attrition may make the interpretation of estimates problematic. Such attrition may be especially severe where there is considerable migration between rural, and urban areas. And attrition is likely to be selective on such characteristics as schooling, so high attrition is likely to bias estimates. The authors consider the extent, and implications of attrition for three longitudinal household surveys from Bolivia, Kenya, and South Africa that report very high annual attrition rates between survey rounds. Their estimates indicate that: 1) the means for a number of critical outcome, and family background variables differ significantly between those who are lost to follow-up, and those who are re-interviewed. 2) A number of family background variables are significant predictors of attrition. 3) Nevertheless, the coefficient estimates for standard family background variables in regressions, and probit equations for the majority of outcome variables in all three data sets, are not significantly affected by attrition. So attrition is apparently not a general problem for obtaining consistent estimates of the coefficients of interest for most of these outcomes. These results, which are very similar to those for industrial countries, suggest that multivariate estimates of behavioral relations may not be biased because of attrition. This wold support the collection of longitudinal data.Statistical&Mathematical Sciences,Public Health Promotion,Health Monitoring&Evaluation,Scientific Research&Science Parks,Educational Sciences,Science Education,Scientific Research&Science Parks,Health Monitoring&Evaluation,Poverty Assessment,Statistical&Mathematical Sciences