ABSTRACT
In Chapter 2, we noted that, from the logical positivist point of view, the experiment is the ideal research strategy. The positivists take this position because, with this research strategy, the experimenter takes complete control of the research situation, determining the independent variable and how it will be manipulated, the dependent variable and how it will be measured, the setting, the participants, and the course of events during the experiment. Experimenters thus create their own artifi cial universes in which to test their hypotheses. This high degree of control over the research situation allows experimenters to establish the conditions that allow them to determine causality: covariation of proposed cause and effect, time precedence of the cause, and lack of alternatives to the independent variable as explanations for any effects found on the dependent measure. These conditions are refl ected in the three defi ning characteristics of the experiment:
1. Manipulation of the independent variable. The experimenter creates the conditions to be studied. For example, in an experiment on the effects of stress, the experimenter creates a high-stress condition and a low-stress condition, and assesses the effects of these conditions on a dependent variable. Manipulation of the independent variable in experimentation stands in contrast to research in which the investigator identifi es natural situations that differ in their stress levels, measures the level of stress in each situation, and correlates stress scores with scores on the dependent variable. If the independent variable in a study is measured rather than manipulated, the study is not an experiment.
