Nonparametric Engel Curves and Revealed Preference

This paper applies revealed preference theory to the nonparametric statistical analysis of consumer demand. Knowledge of expansion paths is shown to improve the power of nonparametric tests of revealed preference. The tightest bounds on indifference surfaces and welfare measures are derived using an algorithm for which revealed preference conditions are shown to guarantee convergence. Nonparametric Engel curves are used to estimate expansion paths and provide a stochastic structure within which to examine the consistency of household level data and revealed preference theory. An application is made to a long time series of repeated cross–sections from the Family Expenditure Survey for Britain. The consistency of these data with revealed preference theory is examined. For periods of consistency with revealed preference, tight bounds are placed on true cost of living indices.     

Secular declines in the association between obesity and mortality in the United States

Recent research suggests that rising obesity will restrain future gains in US life expectancy and that obesity is an important contributor to the current shortfall in us longevity compared to other high-income countries. Estimates of the contribution of obesity to current and future national-level mortality patterns are sensitive to estimates of the magnitude of the association between obesity and mortality at the individual level. We assessed secular trends in the obesity/mortality association among cohorts of middle-aged adults between 1948 and 2006 using three long-running US data sources: the Framingham Heart Study, the National Health and Nutrition Examination Survey, and the National Health Interview Survey. We find substantial declines over time in the magnitude of the association between obesity and overall mortality and, in certain instances, cardiovascular-specific mortality. We conclude that estimates of the contribution of obesity to current national-level mortality patterns should take into account recent reductions in the magnitude of the obesity and mortality association.     

Discrimination Hurts: The Academic,Psychological, and Physical Well‐Being of Adolescents

Little is known about the frequency of ethnic or racial discrimination and its implications for Latin American and Asian youths' development. In this study, we examined if there were ethnic and generation differences among 601 12th graders from Latin American (36%), Asian (43%), and European (19%) backgrounds in the frequency of peer, adult, and daily discrimination, and whether discrimination predicted their well‐being. Adolescents from Latin American and Asian backgrounds reported more adult and peer discrimination than their peers from European backgrounds. Latin American youth reported more adult discrimination than their Asian peers. Discrimination predicted lower grade point averages and self‐esteem, and more depressive symptoms, distress, and physical complaints. Ethnic identity, ethnic socialization, and race rejection sensitivity did not moderate the associations between discrimination and well‐being.     

Testing for qualitative interaction of multiple sources of informative dropout in longitudinal data

Longitudinal studies suffer from patient dropout. The dropout process may be informative if there exists an association between dropout patterns and the rate of change in the response over time. Multiple patterns are plausible in that different causes of dropout might contribute to different patterns. These multiple patterns can be dichotomized into two groups: quantitative and qualitative interaction. Quantitative interaction indicates that each of the multiple sources is biasing the estimate of the rate of change in the same direction, although with differing magnitudes. Alternatively, qualitative interaction results in the multiple sources biasing the estimate of the rate of change in opposing directions. Qualitative interaction is of special concern, since it is less likely to be detected by conventional methods and can lead to highly misleading slope estimates. We explore a test for qualitative interaction based on simultaneous confidence intervals. The test accommodates the realistic situation where reasons for dropout are not fully understood, or even entirely unknown. It allows for an additional level of clustering among participating subjects. We apply these methods to a study exploring tumor growth rates in mice as well as a longitudinal study exploring rates of change in cognitive functioning for Alzheimer's patients.     

Effective casework practice with adolescents: perspectives of statutory child protection practitioners

Many child protection practitioners struggle with the complexity of problems and the limited casework time for adolescent cases. However, there is little research on child protection practice or case management that can guide a practitioner working with adolescents in the child protection system. The aim of this study was to explore and describe the nature of effective child protection practice with adolescents from the perspective of statutory child protection practitioners in one state in Australia. Data were collected through focus group discussions and interviews with child protection practitioners and managers currently working with adolescents (n= 44). A grounded theory approach was used to identify the dominant themes or categories and form linkages and relationships through constant comparison techniques. Seven key categories emerged from this analysis: characteristics of the young person and their family; ‘walking it together’– the centrality of relationships; ‘looking back/looking forward’– practice strategies; practitioner attributes and skills; ‘walking a fine line’– working with the families of adolescents; ‘walking with services’– effective inter‐agency work; and organizational context in effective child protection practice with adolescents. Key implications for practice and areas for further research were discussed.     

Best Nonparametric Bounds on Demand Responses

This paper uses revealed preference inequalities to provide the tightest possible (best) nonparametric bounds on predicted consumer responses to price changes using consumer‐level data over a finite set of relative price changes. These responses are allowed to vary nonparametrically across the income distribution. This is achieved by combining the theory of revealed preference with the semiparametric estimation of consumer expansion paths (Engel curves). We label these expansion path based bounds on demand responses as E‐bounds. Deviations from revealed preference restrictions are measured by preference perturbations which are shown to usefully characterize taste change and to provide a stochastic environment within which violations of revealed preference inequalities can be assessed.