There is a degree of instability in any measurement, so that if it is repeated, it is possible that a different result may be obtained. Such instability, generally described as "measurement error", may affect the conclusions drawn from an investigation, and methods exist for allowing it. It is less widely known that different disciplines, and…

Three issues need to be decided in the design stage of a longitudinal intervention study: the number of persons, the number of repeated measurements per person, and the duration of the study. The degree to which polynomial effects vary across persons and the drop-out pattern also influence the statistical power to detect intervention effects. This…

This study investigated the main effects of social support measures and their stress-buffering effects in two samples of homeless adults (Ns =249 and 219) obtained in the same large county (surrounding Detroit) at different points in time over an 8-year period (1992-1994 and 2000-2002). The findings suggest that the construct of social support,…

Least squares fitting process as a method of data reduction is presented. The general strategy is to consider fitting (linear) models as partitioning data into a fit and residuals. The fit can be parsimoniously represented by a summary of the data. A fit is considered adequate if the residuals are small enough so that manipulating their signs and…

This report describes and evaluates the major computer software packages capable of computing standard errors for statistics estimated from complex samples. It first describes the problem and the proposed solutions. The two major programs presently available, SUPER CARP and OSIRIS, are described in general terms. The kinds of statistics available…