Speech analyses performed on data from 61 speech-delayed children (ages 3-6) found that, in comparison to the validity of conversational speech samples for integrated speech, language, and prosodic analyses, articulation tests appear to yield neither typical nor optimal measures of speech performance. (Author/JDD)

A method is proposed for sequential evaluation of reliability of psychometric instruments. Sample size is unfixed; a test statistic is computed after each person is sampled and a decision is made in each stage of the sampling process. Results from a series of Monte-Carlo experiments establish the method's efficiency. (SLD)

Surveys in which one can observe--after sample selection--that each sample member belongs to one or more aggregations are considered. A formula for the probability that a given aggregation contains at least one sample member is applied to eighth grade data from the National Educational Longitudinal Study of 1988 (NELS:88). (TJH)

Estimating item parameters from a two-parameter normal ogive model is considered using Gibbs sampling to simulate draws from the joint posterior distribution of ability and item parameters. The method gives marginal posterior density estimates for any parameter of interest, as illustrated using data from a 33-item mathematics placement…

Techniques for adjusting census figures are discussed, with a focus on sampling error, uncertainty of estimates resulting from the luck of sample choice. Computer simulations illustrate the ways in which the smoothing algorithm may make adjustments less, rather than more, accurate. (SLD)

This article shows how the methods of survival analysis (also known as event history analysis) lend themselves to the study of the timing of educational events. Using examples from teacher attrition and student dropout research, survival methods are introduced for building statistical models of the risk of event occurrence over time. (Author/SLD)

Analysis of a two-way sample of means is considered when corresponding population means are believed a priori to satisfy a partial order restriction. Simulation and the Gibbs sampler are used to summarize posterior distributions, and the posterior distribution is used to predict GPAs of first-year students at University of Iowa. (SLD)

Examining living organisms in one's own backyard is a key first step toward appreciating the scope and importance of biological diversity throughout the world. The goals of this lab are to involve students in exploring the biodiversity around them, appreciating its scope, and asking questions of new organisms that they may never have noticed…

Describes and evaluates a learning model for information filtering and selective dissemination of information which is an adaptation of the generalized probabilistic model of information retrieval. The model is based on the concept of uncertainty sampling that allows for relevance feedback both on relevant and nonrelevant documents. (Author/LRW)

This paper recommends use of analysis of covariance in early intervention research to account for pretreatment group differences and increase statistical power. Diagrams show how analysis of covariance manipulates data under various conditions. Simulated data analysis demonstrates the process of selecting covariates and shows the results with and…

Applying 2 different models of test construction to test results for a pool of more than 190,000 high school students found no systematic bias against groups with smaller or no representation in the test standardization sample. These results support the integrity of widely used sampling and item selection procedures. (SLD)

Provides details on the instrument development, sample design, data collection, and data analysis procedures of the 1996 National Assessment of Educational Progress (NAEP) long-term trend and main assessments for the United States. (Author/SLD)

Presents a case study that tests a mathematical model for its ability to predict second language vocabulary gains achieved through reading. To overcome the problem of small word gains noted in earlier studies of incidental acquisition, an adult learner of Dutch read a lengthy text and was tested on hundreds of words. The participant's gains were…

Institutional researchers frequently use national datasets such as those provided by the National Center for Education Statistics (NCES). The authors of this chapter explore the adjustments required when analyzing NCES data collected using complex sample designs. (Contains 8 tables.)

Because surveys now can be implemented with relative ease and little cost, many researchers are overlooking the basic principles of survey research. This chapter discusses sources of error that researchers should consider when conducting a survey, and gives readers basic suggestions for reducing error. (Contains 1 table and 1 figure.)