Experimental research
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Experimental research aims to investigate cause-and-effect relationships between variables by manipulating the independent variable and studying its effects on the dependent variable. It differs from other research in that the researcher establishes different treatments to study their effects, allowing them to determine what causes relationships. True experimental designs use random assignment of subjects to treatment groups to control for threats to internal validity like subject characteristics. Poor designs have fewer controls for threats like history, maturation, and testing effects.
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Experimental research
- 1. EXPERIMENTAL RESEARCH CHAPTER 13 Presented by : Nurul Ain binti Abd Manan 2013160689 Nor Zakiah binti Ismail 2013741249 Siti Khalijah binti Zainol 2013977165
- 2. Traditional type of research EXPERIMENTAL RESEARCH concerns relationships between variables Purpose is to investigate cause-and-effect relationships among variables • Experimental groups vs. control groups • Each group of participants receives a different treatment • Always involves manipulation of the independent variable The researcher actually establishes different treatments and then studies their EFFECTS, results from this type of research are likely to lead to the most clear-cut interpretations EXPERIMENTAL RESEARCH
- 3. STEPS IN EXPERIMENTAL RESEARCH State the research problem Determine if experimental methods apply Specify the independent variable(s) Specify the dependent variable(s) State the tentative hypotheses Determine measures to be used Pause to consider potential success Identify intervening (extraneous) variables Formal statement of research hypotheses Design the experiment Final estimate of potential success Conduct the study as planned Analyze the collected data Prepare a research report
- 4. UNIQUENESS EXPERIMENTAL RESEARCH Two ways in which EXPERIMENTAL RESEARCH differs from other educational research. Researcher manipulate the independent variable :- 1. Decide the nature of the treatment - to whom it is to be applied - to what extent 2. Enables researchers to go - beyond description and prediction - beyond the identification of relationship, to at least a partial determination of what causes them.
- 7. CONTROL OF EXTRANEOUS VARIABLES Researchers who conduct experimental studies try to control any and all the subject characteristics. There are some common ways that had been used by researchers to minimize or eliminate threats
- 8. WAYS TO MINIMIZE OR ELIMINATE THREATS Randomization : assume the groups are equivalent Holding certain variable constant : eliminate the possible effects Building the variable into design : include as distinct group Matching : pairs subjects matched to certain variables Using subjects as their own controls :compared the performance Using analysis of covariance : equate groups statistically on the basis of pretest or other variables
- 9. GROUP DESIGNS IN EXPERIMENTAL RESEARCH Good designs control many of the various threats to internal validity (chapter 9) while poor designs control only a few. The quality of an experiment depends on how well the various threats to internal validity are controlled.
- 11. One-Shot Case Study Design It does not provide for any comparison, so the researcher cannot compare the treatment results (as measured by the attitude scale) with the same group before using the new textbook, or with those of another group using a different textbook. The researcher knows nothing about what the group was like before using the text.
- 13. One-Group Pre test-Post test Design This design is better than the one-shot case study (the researcher at least knows whether any change occur). Nine uncontrolled-for threats (history, maturation, instrument decay, data collector characteristics, data collector bias, testing, statistical regression, attitude of subjects, and implementation). The researcher would not know if any differences between pretest and posttest are due to the treatment or to one or more of these threats.
- 14. TRUE EXPERIMENTAL DESIGNS The essential ingredient of a true experimental design is that subjects are randomly assigned to treatment groups. Random assignment is a powerful technique for controlling the subject characteristics threat to internal validity The randomized posttest-only control group design involves two groups formed by random assignment. The randomized pretest-posttest control group design differs from the randomized posttest-only control group design only in the use of a pretest.
- 17. EVALUATING THE LIKELIHOOD OF A TRHREAT The important consideration in planning an experimental study. A number of possible threats may exist. The must ask question by the research is : How likely is it that any particular threat exist in this study?
- 18. AID IN ASSESSING THE LIKELIHOOD Step 1 : What specific factors either are known to affect the dependent variable or may logically to be expected to affect this variable? Step 2 : What is the likelihood of the comparison groups differing on each of these factors? Step 3 : Evaluate the threats on the basis of how likely they are to have an effect, and plan to control for them.
- 19. THREATS TO INTERNAL VALIDITY Subject characteristics Mortality Location Instrumentation Testing History Maturation Attitude of Subjects Regression Implementation
- 20. CONTROL OF EXPERIMENTAL TREATMENTS Intended to improve the internal validity. It has advantages and disadvantages. The researcher control over the experimental treatments- what, who, when and how of it. Researchers seldom have control in educational research.
- 21. QUESTIONS 1) What is experimental research? 2) What are the uniqueness of experimental research? 3) How does the experimental research differ from other type of research? 4) What is random assignment, and what is the difference between random assignment and random selection? 5) How to describe poor experimental design?