Quasi-experimental Design

Quasi-Experimental Design

Nonequivalent before and after design

Nonequivalent Control Group Design: AKA Pretest posttest nonequivalent group uses both control group & experimental group

Used to compare two groups that are likely to be different even before the study begins.

Uses varying number of pretests and posttest.

​​​​Pretest & posttest one group of subject at different interval.

Determine long term effect of treatment.

Using an interruption between tests allowed researcher to assess the strength of treatment over an extended time period.

Given pretest and posttest.

Control group not given treatment or given a treatment not of interest.

Selected and assigned out of convenience (non-random).

Experimental group given treatment of interest.

Time series designs: AKA time series/interrupted time series design, multiple time series design

Posttest is referred to as follow-up test.

Single-subject design

Used to evaluate change when there is no possibility of a control.

Also known as any of the following: Single case design, Case study, Same subject design, Repeated measures design, Clinical research model, Clinical experimental design.