Demonstration of Cause-And-Effect Relationships by True Experimental, Quasi-Experimental, and Single-Case Designs

Demonstration of Cause-And-Effect Relationships by True Experimental, Quasi-Experimental, and Single-Case Designs

Observing the effect on a dependent variable i.e. the outcome by manipulating one or more independent variables (cause) is involved in all experiments. The degree to which the subjects can be assigned by researcher to conditions differentiates the type of experiment. True, Quasi- and Single-case designs are three types of experimental designs.

True Experiment

Subjects are at random assigned, in a true experiment, to the conditions of treatment i.e. independent variable's levels. The only distinctions in the groups would be because of chance. For showing a cause-and-effect relationship, true experiments are excellent. Extraneous variables are controlled by random assignment. They have a tendency to be high on internal validity.

Quasi- Experiments

An important alternative is provided by quasi (“resembling” or “seeming”) experiments when true experiments are not viable. The degree of control that is a trait of true experiments is lacked in Quasi-experiments. In a quasi-experiment, additional evidence must be sought by a researcher for elimination of threats to internal validity. Because relationship in the treatment level is found out by conditions ahead of the control of the researcher, therefore quasi-experiments are often called natural experiments.

Experiments that get benefit of natural happenings are quasi-experiments, for instance, comparison of accomplishment level of later-born children with the first-born children; or equating performance of student at two schools, one having a lower ratio student-teacher as compared to the other. Assigning subjects to treatment level is impossible for the researcher as already the subjects are in pre-existing groups.

Single Case Experiments

A single case studied is involved in a single-subject experiment over a longer period of time. To the changeable levels of the independent variable, one individual or condition is exposed.

Experimental Research

To get answer the question, “What if?” ...