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…

Background: The area of research aimed for a more efficient e-learning is slowly widening from purely technical to the areas of psychology, didactics and methodology. The question is whether the text or background color influence the efficiency of memory, i.e. learning. If the answer to that question is positive, then another question arises which…

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…

Observation is a complex activity; that teachers of science should know how to make observation and how to apply it at all grade levels and finally how to monitor and evaluate their students as a guide. The aims of this experimental design study were to create observation methods and to develop student teachers' process skill of observation. The…

A review of the literature revealed that control (or placebo) vignettes are not used in numerous studies in all areas that employ vignette-based methodology, which is a serious methodological and theoretical flaw. The nature of this flaw and its methodological and theoretical importance is outlined in this paper, as well as procedures and a model…

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…

Many problems confront researchers who are developing appropriate methods to determine the effects of sexual abuse. Particularly serious problems arise when the victims are children who were abused while attending a day care center. Several methods for studying child sexual abuse have been recommended. This paper discusses problems researchers…

The one group posttest only evaluation model has been identified as a relatively inexpensive and useful model that can identify program components that are not being successful. The use of the model is discussed and illustrated through a hypothetical evaluation of a compensatory (Chapter 1) program. The one group posttest only evaluation model…

A persistent problem in the evaluation of field-based projects is the lack of no-treatment comparison groups. Frequently, potential comparison groups are confounded by socioeconomic, racial, or other factors. Among the possible methods for dealing with this problem are various matching procedures, but they are cumbersome to use with multiple…

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.…

The concept of control is fundamental to comparative research. In research designs where randomization of observational units is not possible, control has been exercised statistically from a single covariate by a process of residualization. The alternative, known as subclassification on the propensity score, was developed primarily for…

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,…

Various methods have been suggested for the analysis of data collected in research settings where random assignment of subjects to groups has not occurred. For the purposes of this paper the set of allowable nonrandomized designs is made up of those research designs where data are collected for one or more groups of subjects at two or more time…

A solution is proposed for analysis of variance procedures with missing cells, such as may occur when a control group is not assigned to any of the rows or columns of the various experimental groups. Mathematical models for two-way design are presented which define several variables; as well as row effect, column effect, and row and column…

Problems associated with the analysis of data collected using the Solomon Four Group Design are discussed. The design includes an experimental group and a control group that have been pretested and posttested, and an experimental and a control group that have been posttested only. A sample problem is approached in three different ways. First, the…