On the run length of a Shewhart chart for correlated data

We consider an extension of the classical Shewhart control chart to correlated data which was introduced by Vasilopoulos/Stamboulis (1978). Inequalities for the moments of the run length are given under weak conditions. It is proved analytically that the average run length (ARL) in the in-control state of the correlated process is larger than that in the case of independent variables. The exact ARL is calculated for exchangeable normal variables and autoregressive processes (AR). Moreover, we compare this chart with residual charts. Especially, in the case of an AR(1)—process with positive coefficient, it turns out that the out-of-control ARL of the modified Shewhart chart is smaller than that of the Shewhart chart for the residuals.     

Binding the Generations: Household Formation Patterns among Vietnamese Refugees1

Much of the analysis of refugee and immigrant adaptation has stressed the interaction of prior experience with the requirements of life in a new country. For refugees, that interaction has often been jarring because of the after‐effects of their flight and their relative inability to prepare for a new life in a new country. Yet refugees have often done rather well in economic terms in that new country. The reasons for that relative success have been phrased in cultural terms (e.g., the predisposition toward education) and in general socioeconomic terms (e.g., refugees as educated and skilled). This article examines a set of factors that lie between these customary cultural and socioeconomic categories. Specifically, the paper examines key features of household formation among Vietnamese refugees. An examination of historical data from southern Vietnam indicates patterns in household formation that appear durable over time yet are not shared across the breadth of Vietnam and cannot thus be viewed as “cultural” in the usual sense. A comparison of the historical data with recent national survey data on refugees in the United States indicates that these patterns continue among Vietnamese refugees and are ‐ as compared to other refugees ‐ distinctive to them. These patterns of household formation provide Vietnamese refugees with important options in adaptation to a new country.     

Open Road or Blind Alley? Welfare Reform, Mothers, and Children with Disabilities

Welfare reform was examined for 39 Michigan families whose children have significant health or intellectual and behavioral disabilities. As a group, these families received little specialized assistance or services to address their unique needs. Family-cited barriers to self-sufficiency included poorly trained welfare caseworkers, limited public transportation, and inadequate child care. Having an older child was the only discriminating variable between working and non-working mothers. However, working mothers only had temporary positions with no benefits and low pay. All families, whether employed or not, lived below the poverty line.     

Dementia Problem Behavior and the Production of Informal Caregiving Services

Informal caregivers of individuals with Alzheimer's disease spend a considerable amount of time providing care. In this paper, we use Grossman's health production and Becker's time allocation models to develop a model of informal care provision to elderly dementia patients. In our model, time inputs produce caregiving services, which provides utility to the caregiver, but reduces leisure. We assume that time is less productive of services on the margin as the disease progresses. In this framework, an increase in patients' disease severity does not necessarily increase informal caregiver time input. The cost of formal care establishes a reservation price for informal caregiving. When the costs of informal caregiving rise above this reservation level, the patient is institutionalized. We test empirically the effect of deterioration in the patients' condition, proxied by both disease severity and dementia problem behavior, on informal caregiving time. We find that dementia-related problem behaviors and functional limitations significantly increase inputs of informal caregiving time. Patients' problem behavior exerts a modifying effect on functional limitations, and patients' comorbidities have no effect on informal caregiving time.     

Diagnostics for dependence within time series extremes

Summary. The analysis of extreme values within a stationary time series entails various assumptions concerning its long- and short-range dependence. We present a range of new diagnostic tools for assessing whether these assumptions are appropriate and for identifying structure within extreme events. These tools are based on tail characteristics of joint survivor functions but can be implemented by using existing estimation methods for extremes of univariate independent and identically distributed variables. Our diagnostic aids are illustrated through theoretical examples, simulation studies and by application to rainfall and exchange rate data. On the basis of these diagnostics we can explain characteristics that are found in the observed extreme events of these series and also gain insight into the properties of events that are more extreme than those observed.