Randomized control trials are considered the gold standard for conducting research and estimating causal effects; however, educational research rarely lends itself to experimental design and true randomization. In recent years, there has been a growing interest in finding new approaches to estimate causal effects in nonrandomized studies in…

Our current capacity to understand or provide a context for interpreting the size of an effect in education program evaluation is limited. To address the problem, this study proposes a time-indexed effect size metric (d') to estimate how long it would take for an "untreated" control group to reach the treatment group outcome in terms…

Education research rarely lends itself to large scale experimental research and true randomization, leaving the researcher to quasi-experimental designs. The problem with quasi-experimental research is that underlying factors may impact group selection and lead to potentially biased results. One way to minimize the impact of non-randomization is…

Experimental designs are distinguished as the best method to respond to questions involving causality. The purpose of the present paper is to explicate the logic of experimental design and why it is so vital to questions that demand causal conclusions. In addition, types of internal and external validity threats are discussed. To emphasize the…

The Hawthorne and placebo effects in educational experiments were examined over a 20-year period, as reported in the ERIC, Dissertation Abstracts International, and Psych Info data bases. The literature searches identified 325 studies in education employing the relevant control procedures, and each study was coded for the type of placebo…

A relationship between experimental and statistical controls is considered in an effort to show how this relationship affects the power of an experiment. Statistical rather than experimental controls are often used to reduce the effect of subjects at the extremes of individual difference. This results in attrition of actual experimental subjects.…

A meta-analysis was conducted on 44 educational studies that used either a (labelled) Hawthorne control group, a manipulation of Hawthorne effects, or a group designed to control for the Hawthorne effect. The sample included published journal articles, ERIC documents or unpublished papers, and dissertations. The studies were coded on 20 variables,…

Differential achievement growth patterns between comparison groups is a problem associated with data analysis in compensatory education programs. Children in greatest need of additional assistance, are usually assigned to the program rather than to an alternative treatment so that the comparison groups may vary in several ways, in addition to the…

An attempt was made to see what effect implementation of ethical guidelines would have on cognitive and affective data collected in a classroom setting. A total of 126 graduate and 90 undergraduate male and female subjects were assigned randomly to six treatment groups. The six groups were provided different levels of information on a continuum…

Problems with conducting randomized field experiments in education are explored. Focus is on problems encountered while evaluating a group of dropout prevention projects. Project planners were asked to manipulate the subject eligibility criteria until they identified as eligible three to four times as many students as they could serve. They were…

Four types of control groups are commonly used in cognitive manipulation studies: (1) no-treatment; (2) practice with own methods; (3) practice and training with competing treatments; and (4) practice and training with irrelevant treatments. There are problems associated with the use of each group as a baseline for identifying the "true"…

This paper summarizes a study that assessed the effects of an extended case study that focused on wetland issues with seventh and eighth grade students. The extended case study is an instructional methodology that incorporates the issue investigation/evaluation and action training model. A modified pretest-posttest nonequivalent control group…

A study used pretests/posttests and experimental/control groups to evaluate four business communication skills (BCS) programs conducted with employees at the University of Texas at Austin. Of 91 BCS participants, 86 were women and ages for all participants ranged from 20 to 61 years. Del Gaizo's four levels of evaluation (happiness index, learning…

Forty studies using one or more components of Lozanov's method of suggestive-accelerative learning and teaching were identified from a search of all issues of the "Journal of Suggestive-Accelerative Learning and Teaching." Fourteen studies contained sufficient statistics to compute effect sizes. The studies were coded according to substantive and…