Presentation on theme: "RESEARCH DESIGNS FOR QUANTITATIVE STUDIES. What is a research design? A researcher’s overall plan for obtaining answers to the research questions or."— Presentation transcript:
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
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? INTERVENTION
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 Under what conditions will the intervention be withdrawn or altered?
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
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
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.
1.Studying time related processes - Eg. Healing, earning, growth etc 2.Determining time sequences - Eg. Infertility results in depression 3.Developing comparisons - Eg. Smoking and lung 4. Enhancing research control - Eg. Two groups with alternative interventions Categorization of studies Cross sectional design 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
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.
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
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)
Solomon four group design GroupDate collection BeforeAfter Experimental –with pretest XX Experimental – without pretest -X Control-with pretestXX Control-without pretest -X This design prevents, the post test measures getting affected not only by the treatment but also by exposure to the pre-test
Factorial design Types of stimulation Auditing tactile A1 A2 A1 B1A2 B1 A1 B2A2 B2 A1 B3A2 B3 15min B1 This design permits the testing of multiple hypotheses in a single experimental Daily exposures 45m B3 30min B2
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
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) XO O
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
Advantages and disadvantages of the quasi-experimental research Advantages Feasibility Generalizability some extent Practicality Disadvantage Absent of control
Non Experimental Research Reasons for under taking non-experimental research in nursing oHuman 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. oFor ethical reasons. oNot practical to conduct a true experiment oExperimental design is not appropriate to some research questions
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
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.
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
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.
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.
SURVEY RESEARCH EVALUATION RESEARCH NEEDS ASSESSMENT OUT COMES RESEARCH SECONDARY ANALYSIS META –ANALYSIS DELPHI SURVEYS METHODOLOGIC RESEARCH CONTENT ANALYSIS STUDIES ADDITIONAL TYPES OF QUANTITATIVE RESEARCH