The paper discusses findings of a study that investigated Malawian students' meanings for some probability vocabulary. The study explores the meanings that, prior to instruction, students assign to some words that are commonly used in teaching probability. The aim is to have some insight into the meanings that students bring to the classroom. The…

Three sets of rare baseball events--pitching a no-hit game, hitting for the cycle, and turning a triple play--offer excellent examples of events whose occurrence may be modeled as Poisson processes. That is, the time of occurrence of one of these events doesn't affect when we see the next occurrence of such. We modeled occurrences of these three…

Reports an error in "Finding Useful Questions: On Bayesian Diagnosticity, Probability, Impact, and Information Gain" by Jonathan D. Nelson (Psychological Review, 2005[Oct], Vol 112[4], 979-999). In Table 13, the data should indicate that 7% of females had short hair and 93% of females had long hair. The calculations and discussion in the article…

Purpose: Significant threshold differences on retest for pure-tone audiometry are often evaluated by application of ad hoc rules, such as a shift in a pure-tone average or in 2 adjacent frequencies that exceeds a predefined amount. Rules that are so derived do not consider the probability of observing a particular audiogram. Methods: A general…

Latent class analysis (LCA) is a statistical method used to identify a set of discrete, mutually exclusive latent classes of individuals based on their responses to a set of observed categorical variables. In multiple-group LCA, both the measurement part and structural part of the model can vary across groups, and measurement invariance across…

The purpose of this article is to sketch a hypothetical descriptive framework of statistical knowledge for teaching. Because statistics is a discipline in its own right rather than a branch of mathematics, the knowledge needed to teach statistics is likely to differ from the knowledge needed to teach mathematics. Doing statistics involves many…

Research has consistently shown that older students--those who enter college for the first time at age 25 or older--are less likely to complete a degree or certificate. The authors estimate a single-risk discrete-time hazard model using transcript data on a cohort of first-time community college students in Florida to compare the educational…

Purchase probability as a function of interpurchase time was examined through comparison of findings from laboratory experiments on reinforcement schedules and from marketing investigations of consumers' interpurchase time. Panel data, based on a sample of 80 consumers who purchased nine supermarket food products during 16 weeks, were used. For…

Mediators are variables that explain the association between an independent variable and a dependent variable. Structural equation modeling (SEM) is widely used to test models with mediating effects. This article illustrates how to construct confidence intervals (CIs) of the mediating effects for a variety of models in SEM. Specifically, mediating…

This article proposes an intuitive approach for predictive discriminant analysis with mixed continuous, dichotomous, and ordered categorical variables that are defined via an underlying multivariate normal distribution with a threshold specification. The classification rule is based on the comparison of the observed data logarithm probability…

This study examined the factor structure, reliability, and validity of the Suicide Probability Scale (SPS) in a sample of 226 (80 male, 146 female) adolescent psychiatric inpatients. Confirmatory factor analyses provided only some support for the original subscales. Exploratory factor analyses revealed some overlap with the original scales, but…

A number of methods are available in the literature to measure confidence intervals. Here, confidence intervals for estimating the population mean of a skewed distribution are considered. This note proposes two alternative confidence intervals, namely, Median t and Mad t, which are simple adjustments to the Student's t confidence interval. In…

People's reactions to coincidences are often cited as an illustration of the irrationality of human reasoning about chance. We argue that coincidences may be better understood in terms of rational statistical inference, based on their functional role in processes of causal discovery and theory revision. We present a formal definition of…

This paper provides information about the importance of non-pecuniary school characteristics, such as race and poverty, on teacher turnover in Georgia. Simple descriptive statistics indicate that new teachers are more likely to leave schools with lower test scores, lower income, or higher proportions of minorities. A linear probability and a…

This report summarizes key findings and recommendations from a Community College Research Center (CCRC) study designed to help community colleges develop strategies for improving the rate at which academically underprepared students take and pass initial college-level (or "gatekeeper") courses in math and English. CCRC conducted the…