Research Designs

Introduction

Research design is a term broadly referring to any plan for gathering data systematically in such a way as to be able to arrive at conclusions. On the subject selection dimension, designs may be experimental, quasi-experimental, or non-experimental. On the measurement dimension, designs may be between-subjects or within-subjects.

Experimental studies are characterized by randomizationof subjects into treatment and control groups. Control groups may receive no treatment or some standard treatment, where “treatment” is exposure to some stimulus. Randomization serves to control for variables which are not included explicitly in the study. In quasi-experimental designs, treatment and comparison groups are not composed of randomized subjects, even if data are gathered through random sampling. In the absence of randomization, control for confounding variables must be accomplished explicitly through statistical techniques. Finally, a design is non-experimental if there is...