Analysis of Experimental and Quasi-Experimental Research Designs

This report explores the differences between experimental and quasi-experimental research designs. Experimental design emphasizes high internal validity through random assignment, while quasi-experimental design focuses on manipulating variables without complete randomization. The report highlights the purpose of each design, including their application in evidence-based practice. A case study of an oral rehabilitation study after maxillectomy is provided, which used a quasi-experimental design. The study, which involved 252 patients, examined treatment efficacy. The methodology, including data collection and analysis, is described, along with the replicability of the findings. The report concludes by emphasizing the importance of understanding these research designs for effective research and evidence-based practice in healthcare and other related fields.

1. Experimental research design versus quasi – experimental research design
Experimental research design concerns itself with the construction of research that is of high
internal validity whereas quasi – experimental research design is majorly concerned with
tweaking of independent variable minus the randomness in assignment of subjects to test groups
(Cook & Campbell, 1979). In experimental design the assignment research subjects to
experimental conditions is exogenous while in quasi – experimental research design, it is
endogenous. Exogenous implies that the assignment is random and not influenced by those
involved in the experiment be it the research subjects, treatment providers or researchers.
Endogenous on the other hand implies that the wishes and actions undertaken by those involved
in the research may influence the assignment. Endogeneity poses a problem in that in order to
accurately estimate the causal relationships, it is required that the assignment be at least partially
random. In case of confounding variables, it becomes tricky demonstrating the causal link
between the observed outcomes and the treatment conditions in quasi – experimental design.
This is less of a problem in experimental design due to randomization.
2. Purpose of each research design and its influence on evidence - based practice
a) Experimental research design
It is aimed at determining a relationship between two variables, that is the dependent
and the independent variables where the variables are randomly assigned.
The design has been used in evidence – based practice to analyze the quality of the
evidence offered in support of a given method.
b) Quasi – experimental research design

It is also aimed at establishing whether there is relationship between two variables
that are not randomly assigned but are picked according to some preset criteria.
This design is very useful in social sciences where it is highly difficult to achieve
complete randomization in obtaining results for general trends.
Quantitative research article review
Title: Oral rehabilitation of patients after maxillectomy. A systematic review.
Authors: D.M. dos Santos, F.P. de Caxias, S.B. Bitencourt, K.H. Turcio, A.A. Pesqueira, M.C.
Goiato
Purpose: To identify studies on oral rehabilitation for patients with maxillectomy.
Study methodology
a) Sample
Six papers were selected from 1376 searched. An additional paper was included after
further search of references (dos Santos, Bitencourt, de Caxias, Turico, & Pesqueira). 252
patients were also included and sub – divided into different treatment groups.
b) Design
The study employed quasi – experimental research design.
c) Procedures (Instruments)
The acquired data was made into a spreadsheet detailing the patients’ details, defects
classification, postoperative results and complications, functional results, aesthetics, life
quality, and treatment efficacy.

The independent variables were patients’ details, defects classification, postoperative results and
complications, functional results, aesthetics, life quality while treatment efficacy was the
dependent variable.
The measurement tools were valid as they fully helped at arriving to the desired conclusion by
the researchers.
Replicability of findings:
The findings of the research are easily replicable because the study methodogy is clear and
concise and can be used by independent researchers.
References

Cook, T. D., & Campbell, D. T. (1979). Quasi-experimentation: Design & analysis issues in field settings.
Boston.
dos Santos, D. M., Bitencourt, S. B., de Caxias, F. P., Turico, K. H., & Pesqueira, A. A. (n.d.). Oral
rehabilitation of patients after maxillectomy. A.