Experimental Research

Topics Covered in Session 9

Cause and Effect in Educational Research

Experimental, quasi-experimental, and causal-comparative research methods are frequently studied together because they all try to show cause and effect relationships among two or more variables. To conduct cause and effect research, one variable(s) is considered the causal or independent variable and one variable(s) is considered the effect or dependent variable.

Comments on Experimental Research

Experimental research is defined essentially as research in which the causal (independent) variable(s) can be manipulated in order to change an effect Because of this element of manipulation, researchers in using experimental methods are expected to maintain a good degree of control throughout the period of the study to establish with confidence that cause and effect occurred.

A classic experimental research design in education involves establishing two random groups of students:* one group is a control group that is taught in a traditional manner; a second group is the experimental group that is taught in a new/non-traditional manner. Pre and post tests of student achievement are conducted to determine if a statistically significant difference occurred in achievement. If the achievement in the experimental group is statistically higher than the achievement in the control group, the experiment was a success in demonstrating that the new teaching technique was the cause for the higher achievement effect.

*NOTE: Quasi-experimental research is a form of experimental research in which random samples cannot be identified.

Data Sources

Research Tools

Procedural Considerations

The most important procedural consideration in doing experimental research is to identify a group in which the values of the dependent variable are as identical as possible. Members of the group are randomly assigned to a control subgroup and to an experimental subgroup. The members of the experimental subgroup are then subjected to some treatment (independent variable) which the researcher can manipulate or change. The members of the control subgroup are not subjected to the treatment. For example, a group of 3rd grade students with the same mathematics achievement test scores are divided randomly into two subgroups: the experimental subgroup receives mathematics instruction using manipulatives; and the control subgroup receives mathematics instruction without the use of manipulatives. After some appropriate period of time, the two subgroups are tested to determine if the experimental subgroup has achieved higher academically than the control group.
Hypotheses are generally used
Statistics are extensively used in experimental research and include measures of spread or dispersion such as: t-tests; Chi-Square; analysis of variance as well as measures of relationship such as: Pearson Product-Moment Coefficient; Spearman Rank Order Coefficient; Phi Correlation Coefficient; regression.