Discussion of sampling methods used in information science research focuses on Fussler's method for sampling catalog cards and on sampling by length. Highlights include simple random sampling, sampling with probability equal to size without replacement, sampling with replacement, and examples of estimating the number of books on shelves in certain…

Problems in selection of optimal designs in item-response theory (IRT) models are resolved through a sequential design procedure that is a modification of the D-optimality procedure proposed by Wynn (1970). This algorithm leads to consistent estimates, and the errors in selecting the abilities generally do not greatly affect optimality. (SLD)

A practical theory is offered for probing external validity, the generalization of causal relationships. This alternative theory is built around five principles abstracted from research on construct validation. It emphasizes purposive sampling for theoretical ends rather than random sampling to represent a population. (SLD)

Assesses the reliability of the National Longitudinal Survey of Youth (NLSY) data in terms of attrition patterns, characteristics of attriters and returners, and comparability with the Current Population Survey (CPS). Explores how attrition might corrupt the picture of labor-market experience and attempts to reconcile discrepancies between the CPS…

This study examined the representativeness of a time-sampling observational procedure to evaluate students with behavior disorders by examining error in samples of varying size in comparison to a criterion measure. Analyses of both single subject and multiple subject designs suggested that samples of 16 to 20 observational sessions of eight-minute…

Discussion of speech sampling in the assessment of children with phonological disorders focuses on the use of nonlinear phonological analysis, a method whereby multiple aspects or levels of a child's phonological system are examined. Principles and suggestions offer general guidance for adequate sample elicitation. (Contains references.)…

Limiting data collection to a sample group is one way to increase effectiveness in dealing with data. The paper describes how to draw a sample group (random sampling, stratified random sampling, purposeful sampling, and convenient or opportunity sampling) and discusses how to determine the size of the sample group. (SM)

Presents an experiment on the sampling process including sample size and particle size. (YDS)

Presents a laboratory experiment in which students study the sampling of solids and statistical analysis. (YDS)

Using Microsoft Excel, several interactive, computerized learning modules are developed to demonstrate the Central Limit Theorem. These modules are used in the classroom to enhance the comprehension of this theorem. The Central Limit Theorem is a very important theorem in statistics, and yet because it is not intuitively obvious, statistics…

Objective: To describe the prevalence of DSM-IV disorders and the pattern of comorbidity in a population-based sample of 7- to 14-year-old Brazilian schoolchildren. Method: Random sampling of schools (stratified into private, public rural, and public urban) was followed by random sampling of pupils from school lists. In 2000-2001, a total of 1,251…

To determine the extent to which published randomized controlled trials (RCTs) of psychotherapy can be generalized to a sample of outpatients, the authors matched information obtained from charts of patients who had been screened out of RCTs to inclusion and exclusion criteria from published RCT studies. Most of the patients in the sample who had…

If a random sampling of student affairs professionals was taken, they'd all agree: without the work they do with students, campus functions would simply grind to a halt. "Student affairs professionals spend 80 percent of their time with students. We do admissions and registration, we house them and feed them, we do the counseling and guidance…

Context and Purpose: This study examined the predictors of HIV testing and factors associated with intention to accept a free HIV test among 244 Hispanic migrant/seasonal farmworkers in South Florida. Methods: Time and space sampling procedures were used to recruit participants in public venues. Bilingual staff interviewed eligible respondents in…

Addressing methodological weaknesses of previous research, this study assesses whether African American women are, in fact, less likely to participate in breast cancer support groups than are White women. Of the breast cancer survivors, 958 (26% African Americans, 73% Caucasian) completed interviews concerning demographic characteristics, other…