An introduction to econometric applications of empirical process theory for dependent random variables

This paper discusses some uses in econometrics of empirical process theory for dependent rendom variables. Examples considered include non-standard parametric hypotheses tests and semiparametric estimation. The application of bracketing functional limit results is discussed in some detail     

Screening for patients with alcohol problems: severity of patients identified by the CAGE.

Primary care physicians are well situated to identify patients with substance abuse problems and motivate them to seek appropriate assistance, but active programs are the exception. A study in a community setting was undertaken to assess the CAGE (the first letters of key words in a series of four questions about drinking: cut down; annoyed; guilty; and eye-opener), instrument in the routine screening for alcohol problems in both new and established patients. The screening process identified subjects for a pilot evaluation of a motivational interview designed to encourage problem-solving behavior. This article focuses on the screening results and the use of the CAGE instrument. During June and July of 1990, 687 patients of two primary care physicians belonging to a large group practice were asked to complete a health questionnaire that included the CAGE. Those who responded affirmatively to at least two of the four CAGE questions were requested to participate in follow-up assessment of problems associated with alcohol and health. The type and severity of alcohol problems experienced by patients who scored positive on the CAGE are described. Prevalence of a positive score on the CAGE was 8.6 percent with males, smokers, and blue collar and unemployed persons being more likely to score positive. The positive predictive value was .68. Primarily, persons with moderate alcohol problems were identified. Results show that the CAGE instrument is a useful screening device for identifying those with mild to moderate substance abuse problems, increasing the opportunity for intervention prior to serious medical complications. The instrument is easily administered, and has demonstrated relatively high levels of sensitivity and specificity. When combined with assessment and motivational interviews, the CAGE shows promise in the secondary prevention of substance abuse and related health problems.     

EFFECTS OF A PREPAID NONMONETARY INCENTIVE ON RESPONSE RATES AND RESPONSE QUALITY IN A FACE-TO-FACE SURVEY

We conducted a randomized experiment on a face-to-face interviewsurvey in order to test the effects on response rates of a prepaidnonmonetary incentive. Results showed a statistically significantincrease in response rates, mostly through reduction in refusalrates, in the half sample that received the incentive (a gift-typeballpoint pen) as compared with a no incentive control group.The effect appears to be due to greater cooperation from incentiverecipients at the initial visit by an interviewer. Unexpectedly,the incentive group also showed a significantly higher rateof sample ineligibility, possibly due to easier identificationof vacant residences or nonexistent addresses. In addition,evidence suggests greater response completeness among respondingincentive recipients early in the interview, with no evidenceof increased measurement error due to the incentive.     

Estimation of noncentrality parameters

We propose some estimators of noncentrality parameters which improve upon usual unbiased estimators under quadratic loss. The distributions we consider are the noncentral chi-square and the noncentral F. However, we give more general results for the family of elliptically contoured distributions and propose a robust dominating estimator.