Quasi Experimental Research Design

Quasi Experimental research design

1. QUASI EXPERIMENTAL RESEARCH DESIGN

2. QUASI EXPERIMENTAL DESIGN The prefix “quasi” means, in essence, “sort of”, or resembling. The word “quasi” means as if or almost, so a quasi-experiment means almost a true experiment. Quasi-experimental studies take on many forms, but may best be defined as lacking key components of a true experiment.

3. QUASI EXPERIMENTAL DESIGN A true experiment includes: (1) randomization; (2 ) experimental group and control group ; and ( 3 ) Researcher-manipulated variable Quasi-experiments involve the manipulation of an independent variable. However , it lacks one or both of the essential properties: randomization and a control group.

4. QUASI EXPERIMENTAL DESIGN It is used when real experiments are not feasible and having a control group would be unethical. E.g. Giving ill people a placebo medication. It is used to examine effects that rely on person factors.

5. ADVANTAGES Without extensive pre-screening and randomization, it reduces the time and resources needed for experimentation. This design is more suitable for real-world natural setting than true experimental research designs. It reduces the difficulty and ethical concerns that may surround the pre-selection and random assignment of test subjects. 

6. DISADVANTAGES The absence of a control group or lack of control over the research setting makes the results of this design less reliable and weak for the establishment of casual relationship between independent and dependent variables. Pre-existing factors and other influences are not taken into account because variables are less controlled in quasi-experimental research.

7. Validity in Quasi-experimental Research Internal Validity- refers to the validity of the findings within the research study . Problems that can affect internal validity are: -History -Mortality -Maturation - Selection Interaction -Instrumentation - Statistical Regression -Selection For example, Mortality affects the research done if the number of students tested is not consistent. Students who leave or move to the school will affect the data .

8. External validity  refers to the extent to which the results of study can be generalized or applied to other members of the larger population being studied. For example, if a single class made the change on 1 elementary school, external validity questions whether the entire school or the entire district will be able to make the change Validity in Quasi-experimental Research

9. Quasi-Experimental Designs

10. 3 Most Popular Quasi-experimental Designs Non-equivalent Control Group Time Series Design Multiple Time Series Design

11. Quasi-Experimental Design: Non Equivalent Control Group Design 2 groups are compared/2 sample groups practical when implementing practical when analyzing can be affected by many extraneous variables popular design among educators

12. Quasi-Experimental Designs Non-equivalent control group designs Types 1.Non equivalent control group pre-test post-test design O1 X O2 O1 - O2 2.Non-equivalent control group post test only design X O O KEY: X =treatment or intervention O1 =pre-test O2 =post-test

13. Quasi-Experimental Design: Time Series Design uses one sample group involves repeated observations or measurements over a period of time both before and after treatment . measures significant change

14. Quasi-Experimental Designs Time Series Designs Types 1. Time Series design O1 O2 O3 O4 X O5 O6 O7 O8 2. Time Series non-equivalent control group design O1 O2 O3 O4 X O5 O6 O7 O8 O1 O2 O3 O4 - O5 O6 O7 O8 3. Time Series with intensified treatment (quasi-experimental) O1 O2 X O3 O4 X+1 O5 O6 X+2 O7 O8 4. Time series with withdrawn and reinstituted treatment O1 O2 X O3 O4 ( -X ) O5 O6 X+2 O7 O8

15. Quasi-Experimental Design: Multiple Time Series Design Adds a control group to time series design Adds credibility to findings