RESEARCH DESIGNS FOR QUANTITATIVE STUDIES

1. RESEARCH DESIGNS FOR QUANTITATIVE STUDIES

2. What is a research design? • A researcher’s overall plan for obtaining answers to the research questions or for testing the research hypotheses is referred to as the research design. Aspects of research design • Intervention • Comparison • Controls of extraneous variables • Timing of data collection • Research sites and settings • Communication with the study participants

3. INTERVENTION The following questions would be addressed • What exactly is the intervention? • What are the procedures to be used for both groups? • Who will receive the intervention and who will not? How will each group be selected? • What is the dosage of the intervention?

4. INTERVENTION – Cont… • How long will the intervention be administered? And when will it begin? • Who will administer the intervention? • Will those administering the intervention are fully informed about the study? Will study participants be fully informed? • Under what conditions will the intervention be withdrawn or altered?

5. COMPARISONS • In a quantitative study, the researcher specifies the nature of the comparisons in advance, where as in a qualitative study, comparisons may suggest themselves during the course of data collection. TYPES OF COMPARISONS IN RESEARCH STUDIES • Comparison between two or more groups • Comparison of a single group at two or more points in time • Comparison of a single group under different circumferences or experience • Comparison based on relative rankings • Comparison with samples from other studies

6. CONTROLS FOR EXTRANEOUS VARIABLES The researcher must make decisions about which extraneous variables to control. TIMING OF DATA COLLECTION RESEARCH SITES & SETTINGS COMMUNICATION WITH THE STUDY PARTICIPANTS

7. Overview of Research Design Types • Structured versus flexible designs Eg. Quantitative study and qualitative study • Between –subjects and within –subjects designs Eg. Testing the efficacy of a drug 1. One group administered one group do not administered Between subjects design 2. Same group before, after treatment Within subjects design • The time dimension There are four situations in which it might be appropriate to design a study with multiple points of data collection.

8. Studying time related processes - Eg. Healing, earning, growth etc • Determining time sequences - Eg. Infertility results in depression • Developing comparisons - Eg. Smoking and lung 4. Enhancing research control - Eg. Two groups with alternative interventions Categorization of studies • Cross sectional design • Longitudinal design

9. Longitudinal design Types • Trend studies • Cohort studies • Cross-sequential design (Control studies with a cross –sectional approach) • Panel studies • Follow-up studies Retrospective versus prospective designs

10. Characteristics of good design • Appropriateness to the research question • Lack of bias • Precision • Power Tips on designing research • Make a written list of the pros and cons of each • Balance a number of considerations, such as time, cost, ethical issues and the integrity of the study. • Anticipate alternative findings and consider whether design adjustments might affect the results. • Seek the advice of research experts in deciding the design • Write out a rationale for your choices one you have made your design decisions.

11. Experimental Research designs for quantitative studies Characteristics of true experiments • Manipulation – Involves doing something to at least one group of subjects • Control – Refers to a group of subjects without any manipulation • Randomization – involves the Placement of subjects in groups on a random basis Research designs • Experimental designs • Quasi experimental designs • Non experimental designs

12. Types of experimental designs • Basic experimental design • Solomon four group design • Factorial design • Repeated measures design • Randomized clinical trials Basic experimental design Types • After only design or post test –only design (R-X-O) • Before after design or pretest –posttest design (R-O1 X O2) (R-O1 – O2)

13. Solomon four group design This design prevents, the post test measures getting affected not only by the treatment but also by exposure to the pre-test

14. Factorial design Types of stimulationAuditing tactile A1 A2 Daily exposures 15min B1This design permits the testing of multiple hypotheses in a single experimental 30min B2 45m B3

15. Repeated measures design Randomized clinical trials • Advantages and disadvantages of experimental studies. Advantage– Confidence with which causal relationships can be inferred – Most powerful method available to scientists • Disadvantage– Hawthorne effect limitation – Number of like characteristics of human beings, finance etc

16. QUASI, EXPERIMENTAL RESEARCH Quasi-Experimental designs Non equivalent control group designs Types 1.Non equivalent control group pre-test post –test design (Quasi experimental) O1 X O2 O1 - O2 2. Non equivalent control group post test only design (Pre experimental) X O O

17. Time series designs Types 1. Time series design (Quasi –experimental) O1 O2 O3 O4 X O5 O6 O7 O8 2. Time series non-equivalent control group design (quasi- experimental) 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 (quasi-experimental) O1 O2 X O3 O4 (–X) O5 O6 X O7 O8

18. Advantages and disadvantages of the quasi-experimental research Advantages Feasibility Generalizability some extent Practicality Disadvantage Absent of control

19. Non Experimental Research Reasons for under taking non-experimental research in nursing • Human characteristics are inherently not subject to experimental manipulation (eg. blood type personality etc) and the effects of these characteristics on some phenomenon of interest cannot be studied experimentally. • For ethical reasons. • Not practical to conduct a true experiment • Experimental design is not appropriate to some research questions

20. Types of Non Experimental Research • Ex post facto or correlational research • Descriptive research 1. Ex post facto design on correlational research Schematic diagram Ex post facto design Group A O Group B O

21. Descriptive research Purpose - To observe, describe and document aspects of situation as it naturally occurs - To serve as a starting point of for hypothesis generation or theory development.

22. Types • Descriptive correlational study – No control over the independent variables • Univariate descriptive studies – Not focused on only one variable but to describe the existing factors in terms of frequency of occurrence

23. Advantages: • An efficient and effective means of collecting a large amount of data about a problem area • Short time only • No biophysiologic or other measures are needed • Has an intrinsic appeal for the solution of many practical problems.

24. Disadvantages: • Weak in its ability to reveal causal relationships • Susceptible to the possibility of faulty interpretation • Preexisting differences may be a plausible alternative explanation for any observed differences on the dependent variable of interest.

25. ADDITIONAL TYPES OF QUANTITATIVE RESEARCH SURVEY RESEARCH EVALUATION RESEARCH NEEDS ASSESSMENT • OUT COMES RESEARCH • SECONDARY ANALYSIS • META –ANALYSIS • DELPHI SURVEYS • METHODOLOGIC RESEARCH • METHODOLOGIC RESEARCH • CONTENT ANALYSIS STUDIES

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