Experiments and Quasi Experiments. Profesor Alexander Settles. Types of Experiments. There are four kinds of experiments: True experiments Quasi-experiments Natural experiments Naturalistic experiments. True Experiments.
Experiments and Quasi Experiments Profesor Alexander Settles
Types of Experiments There are four kinds of experiments: • True experiments • Quasi-experiments • Natural experiments • Naturalistic experiments
True Experiments • Some true experiments are done in the lab, others are done in the field. • There are five steps to follow in conducting true experiments:
True Experiments 1. Need at least two groups: anexperimental group and a control group. One groups gets the intervention, the other group does not. 2. Random assignment of individuals to the groups. (The degree to which random assignment ensures equivalence of the groups is dependant upon the size of the groups.)
True Experiments 3. The groups are measured on one or more dependent variables. This is called the pretest. 4. The intervention (independent variable) is introduced. 5. The dependent variables are measured again. This is the post test.
Quasi-Experiments • Are experiments where the ability to randomly assign individuals to the experimental and control groups is limited or nonexistent. • Quasi-experiments are more commonly used in evaluating management policy
Quasi-Experiments Example In a study of the effectiveness of a new management technique one branch office is given a new TQM method to implement another branch office retains the traditional management policy
Quasi-Experiments Example (cont.) At the end of the a year the branch with TQM has higher quality of production than the one that retained the traditional management technique. Is this a “quasi-experiment”? Why?
Quasi-Experiments Example (cont.) Answer: Most likely -- YES Random assignment to the two classes was probably not made, hence, groups may not be equivalent. Possibility of results being confounded other factors remains.
Natural Experiments Natural experiments are happening around us all the time. They are not conducted by researchers, but simply evaluated by researchers. In other words, the researcher does not have control over the application of the treatment. This also means that there is no control over what groups receive the treatment and the composition of those groups.
Naturalistic Experiments In naturalistic experiments, one contrives to collect experimental data under natural conditions. You make the data happen out in the natural world (not in the lab), and you evaluate the results.
Naturalistic Experiments The difference between a natural experiment and a naturalistic experiment is that the first just happens, the second must be contrived to happen.
Naturalistic Experiments Naturalistic experiments deviate from true experiments because group membership is not randomly assigned, and exogenous factors (confounding variables) are not controlled.
Naturalistic Experiments Examples: • Patience of drivers behind a car that did not move soon after a red light turned green (independent variables: newness of car and dress of driver) • Matched pair testing to uncover discrimination in hiring practices • Determining a manager’s fulfillment of new learning organization policy by placing an employee in the team with training and monitoring responsibility