The present article provides a primer on using effect sizes in research. A small heuristic data set is used in order to make the discussion concrete. Additionally, various admonitions for best practice in reporting and interpreting effect sizes are presented. Among these is the admonition to not use Cohen's benchmarks for "small," "medium," and…

Very little explanatory power is required in order for regressions to exhibit statistical significance. This article discusses some of the causes and implications. (Contains 2 tables.)

This paper offers a practical guide to use null hypotheses significance testing and its alternatives. The focus is on improving the quality of statistical inference in quantitative communication research. More consistent reporting of descriptive statistics, estimates of effect size, confidence intervals around effect sizes, and increasing the…

An important part of teaching students how to use the BLAST tool for searching large sequence databases, is to train the students to think critically about the quality of the sequence hits found--both in terms of the statistical significance and how informative the individual hits are. This paper describes how generating truly random sequences by…

In 1988, the National Center for Education Statistics (NCES) introduced a proposal to develop a private school data collection that would improve on the sporadic collection of private school data dating back to 1890 and improve on commercially available private school sampling frames. Since 1989, the U.S. Bureau of the Census has conducted the…

The primary goals of this project were to develop a reliable instrument to measure the chemistry course perceptions (CCP) of undergraduate chemistry students and to determine the predictors of CCP of undergraduate students as they enter their first college chemistry class. In a pilot study, 250 undergraduate students were solicited with 57…

In the rapidly changing globalized world, school librarians cannot prepare today's students for every possible outcome, but they can give them the skills that will make them adaptable in 21st-century learning and work settings. The mission for school library programs is to ensure that students are effective users of ideas and information by being…

In this note the Nearest Neighbour Index is investigated in three cases, linear, 2-dimensional and 3-dimensional. In each case the formula is investigated and the numerical values for the data points to be viewed as attracting each other, repelling each other or being randomly distributed are justified. Also, in each of the three cases mentioned…

The fail-safe N is typically a "what if" analysis applied to studies rather than to a single study. This statistical procedure provides information regarding the stability of a meta-analysis by demonstrating how many nil-null articles would be needed to change the statistically significant results to a statistically nonsignificant…

Hypothesis testing is one of the more difficult concepts for students to master in a basic, undergraduate statistics course. Students often are puzzled as to why statisticians simply don't calculate the probability that a hypothesis is true. This article presents an exercise that forces students to lay out on their own a procedure for testing a…

Extreme-value statistics is often used to estimate so-called return values (actually related to quantiles) for environmental quantities like wind speed or wave height. A basic method for estimation is the method of block maxima which consists in partitioning observations in blocks, where maxima from each block could be considered independent.…

The increased interest in reporting effect sizes means that it is necessary to consider what should be included in a primer on effect sizes. A review of papers on effect sizes and commonly repeated statistical analyses suggests that it is important to discuss effect sizes relative to bivariate correlation, t-tests, analysis of variance/covariance,…

Over the last few years, there has been evolution, although not a linear one, that has progressed from an emphasis on statistical significance to an emphasis on effect size to an emphasis on both of these concepts to what is believed to be a pragmatic emphasis on replicability. This paper presented two methods of estimating a study's replicability…

The purpose of this paper is to illustrate how displaying disattenuated correlation coefficients along with their unadjusted counterparts will allow the reader to assess the impact of unreliability on each bivariate relationship. The paper also demonstrates how a proposed new "what if reliability" analysis can complement the conventional null…

Provides an overall test statistic to evaluate significance that yields 100% (1-alpha) confidence intervals for all linear combinations of effect sizes, shows how the stepdown Finite Intersection Test (N. Timm, 1995) may be used to test whether effect sizes are simultaneously different from zero, and illustrates the procedure. (SLD)