Assignment: classifying nonexperimental research

Assignment: classifying nonexperimental research

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ASSIGNMENT: CLASSIFYING NONEXPERIMENTAL RESEARCH

Phrasing Questions

In the first case demonstrated in Figure 4.1, you would be comparing groups with different levels of education on some measure (salary), and in the second case, you would be relating two sets of numeric scores (years and salary). The research questions of interest in the two cases would be: (1) how do groups, based on highest degree earned, differ from each other with respect to salary? and (2) how does number of years of schooling relate to salary? Phrased generically, the key questions in the two situations are: How do groups differ from each other on some measure? How are the variables related to each other? The distinction between these two cases depends only on the fact that education was conceptualized as either categorical or quantitative and not on the nature of the relationship involved.

REFLECTION QUESTIONS

By now, you should be able to:

1. Describe the difference between experimental and nonexperimental studies

2. Give an example of an independent and a dependent variable within the context of a research question

3. Give an example of a categorical and a measured, quantitative variable

CLASSIFYING NONEXPERIMENTAL RESEARCH

In the literature on experimental studies, there is agreement on the distinction between true- and quasi-experiments. Although both involve treatment manipulation, trueexperiments use random assignment of subjects to groups and random assignment of groups to treatments. Quasi-experiments use preexisting intact groups, which are randomly assigned to treatment conditions.

For nonexperimental designs, there appears to be no consistent agreement on typology. In 1991, Elazar Pedhazur and Liora Schmelkin stated that “there is no consensus regarding the term used to refer to designs” which were presented in their chapter on nonexperimental designs (p. 305). Two commonly used terms for nonexperimental studies are “correlational research” and “survey research.” However, the term correlation relates more to an analysis strategy than to a research design and the term survey describes a method of gathering data that can be used in different types of research.

Ten years later, Burke Johnson (2001) came to the same conclusion. Based on a review of twenty-three leading methods textbooks in education and related fields (thirteen explicitly from education and the rest from anthropology, psychology, political science, and sociology), he found little consistency in how nonexperimental studies were classified. He discovered over two dozen different labels being used, sometimes

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Nonexperimental Quantitative Research

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with slight variations in the wording. The most frequently used labels in these texts were survey (twelve times), correlational (ten times), descriptive (eight times), and causal-comparative (five times). The result of my informal review of six additional research methods texts was consistent with Johnson’s findings.

In an attempt to remedy this confusion, Johnson (2001) proposed a categorization scheme consisting of two basic dimensions, each with three categories. The first dimension represents a characterization of the basic goal or main purpose for conducting the nonexperimental quantitative study. The second dimension allows the research to be classified according to the time frame in which data were collected. These two dimensions will be presented here and discussed separately in the next two sections. In your reading of published articles or research methods textbooks, you will probably encounter other terms for nonexperimental research. You may want to read Johnson (2001) to familiarize yourself with these terms and with the problems that arise because of their use.