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# Quantitative Research Design * DR. A. Asgari

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### Quantitative Research Design * DR. A. Asgari

1. 1. QUANTITATIVE RESEARCH DESIGN Dr. Azadeh Asgari Research Methodology
2. 2. Correlational Research <ul><li>To study to what extent variation in one factor is related to variation on one or more factors based on a coefficient index. </li></ul><ul><li>PURPOSE – to establish there is relationship, and strength of relationship between two or more quantitative variables based on a coefficient value. </li></ul><ul><li>Purpose – to ascertain there exist a relationship or to use relationships to predict. </li></ul>
3. 3. Correlational Research <ul><ul><li>Example: </li></ul></ul><ul><ul><ul><li>Relationship between achievement in English and achievement in mathematics </li></ul></ul></ul><ul><li>Variables that have strong relationships vs variable that is the cause and it affects another variable. </li></ul><ul><ul><li>Example: </li></ul></ul><ul><ul><li>Relationship between self concept and achievement) </li></ul></ul>
4. 4. Coefficient of Determination <ul><li>Assesses the proportion of variability in one variable that can be determined or explained by A second variable. </li></ul><ul><li>e.g. </li></ul><ul><ul><li>R = .7 </li></ul></ul><ul><ul><li>R 2 = .49 = 49% </li></ul></ul><ul><ul><li>I.E. 49% of the variability in Y can be determined or explained by X </li></ul></ul><ul><ul><li>E.G. Parents' education level explains 49% of students satisfaction </li></ul></ul>
5. 5. Examples of Correlational Research <ul><li>Relationships between grades obtained through criterion reference for several subjects. </li></ul><ul><li>A study to predict success at the graduate level based on inter-correlational patterns of variables at the undergraduate level. </li></ul>
6. 6. SCATTERGRAM OF ‘r’ Y HIGH X HIGH LOW LOW PERFECT POSITIVE CORRELATION (+1.00)
7. 7. SCATTERGRAM OF ‘r’ Y PERFECT NEGATIVE CORRELATION ( - 1.00) HIGH X HIGH LOW LOW
8. 8. SCATTERGRAM OF ‘r’ Y HIGH POSITIVE CORRELATION ( .83) HIGH X HIGH LOW LOW
9. 9. SCATTERGRAM OF ‘r’ Y SUBSTANTIAL NEGATIVE CORRELATION ( - .76) HIGH X HIGH LOW LOW
10. 10. SCATTERGRAM OF ‘r’ Y MODERATE POSITIVE CORRELATION (.57) HIGH X HIGH LOW LOW
11. 11. SCATTERGRAM OF ‘r’ Y ZERO CORRELATION (0.00) HIGH X HIGH LOW LOW
12. 12. Coefficient of Correlation (bivariate) <ul><li>Pearson’s product moment coefficient of correlation </li></ul><ul><li>Point biserial correlation </li></ul><ul><li>Biserial correlation </li></ul><ul><li>Phi ( φ ) coefficient </li></ul><ul><li>Contingency coefficient </li></ul><ul><li>Spearman’s rho coefficient of correlation </li></ul>
13. 13. Multivariate Correlation <ul><li>MULTIPLE REGRESSION </li></ul><ul><li>DISCRIMINANT ANALYSIS </li></ul><ul><li>CANONICAL CORRELATION </li></ul><ul><li>PATH ANALYSIS </li></ul>
14. 14. Ex-post Facto Research <ul><li>Also known as causal comparative research. </li></ul><ul><li>Purpose = to study cause-effect relationships by observing ‘effect’ that exist and relooking again the data to understand the causal factor. </li></ul><ul><li>Differ from experimental research in which data collection is done in a controlled situation. </li></ul>
15. 15. Ex-post Facto Research <ul><li>Some Examples: </li></ul><ul><li>To identify the attributes of an effective teacher which has been defined as performance in the annual assessment and comparing data on students’ performance for the last 10 years from his/her personal file. </li></ul><ul><li>To see behavioural patterns and student achievement of year one students who had undergone or not undergone kindergarten before entering school. </li></ul><ul><li>To identify the attributes of an effective teacher which has been defined as performance in the annual assessment and comparing data on students’ performance for the last 10 years from his/her personal file. </li></ul>
16. 16. Ex-post Facto Research <ul><li>Researched after a situation or an event has happened. </li></ul><ul><li>The researcher will look at one or more ‘effects’ and study the data by reflecting on previous evidences to seek the answers to the cause, relationships and give explanations. </li></ul>
17. 17. Ex-post Facto Research <ul><li>Strengths: </li></ul><ul><li>Very suitable for situations where experimental research which is stronger, is unable to be done: </li></ul><ul><ul><li>If in a situation where factors such as selection, control and manipulation of variables are unable to be done to see direct cause-effect relationships. </li></ul></ul><ul><ul><li>If laboratory control for the purpose of research is not practical, too expensive, or not ethical if conducted. </li></ul></ul>
18. 18. Ex-post Facto Research <ul><li>Strengths: </li></ul><ul><li>This method provides useful information on phenomena which had happened : </li></ul><ul><ul><li>Which variable is related to which variable? </li></ul></ul><ul><ul><li>Under which situation? </li></ul></ul><ul><ul><li>How is the sequence, how is the pattern like? </li></ul></ul>
19. 19. Weaknesses of Ex-post Facto’ Research <ul><li>Main – lack of control over independent variable – not able to manipulate the variable which affect the ‘effect’– therefore, the need to study as many possible causes which may provide the results – problem = cannot be sure of the cause-effect relationships. </li></ul><ul><li>Problem of ascertaining that all causal factors have been included in the research. </li></ul><ul><li>Complications due to the fact that may be not one factor is the cause – maybe combinations of several factors or interactions of several factors are the cause. </li></ul>
20. 20. Steps to Do Ex-post Facto Research <ul><li>Identify the problem </li></ul><ul><li>Survey related literature </li></ul><ul><li>State the hypothesis </li></ul><ul><li>List all possible assumptions that become the basis of the hypothesis </li></ul><ul><li>Approach: a) Choose the subjects </li></ul><ul><ul><li>b) Select data collection technique </li></ul></ul><ul><ul><li>c) Specify the category to classify the data which may not be directly related, but may have relationships. </li></ul></ul><ul><li>Check for the validity of data collection </li></ul><ul><li>Provide explanations, analysis, and interpretation of results. </li></ul>
21. 21. Experimental Research <ul><li>Unlike ex post facto and correlational studies which stress on relationships / associations, experimental research could explain cause-effect relationships between variables. </li></ul><ul><li>A design that involves the manipulation of one variable (treatment) followed by observations made on the effect of the manipulation on one or more dependent variables </li></ul>
22. 22. Experimental Research <ul><li>The variables that are manipulated are the experimental variable or treatment variable or independent variable. </li></ul><ul><li>Most experimental research in education uses a group that is compared to the experimental group and do not receive the treatment = control group. </li></ul>
23. 23. Experimental Research <ul><li>Example: </li></ul><ul><li>pre-experiment (one-group pretest and posttest) </li></ul><ul><li> O 1 x O 2 </li></ul><ul><li>Problems in experiment – to ascertain the suitable control group so that any change in the posttest should be identified due to the treatment which the researcher has manipulated (true) </li></ul><ul><li>r O 1 x O 2 </li></ul><ul><li>R O 1 O 2 </li></ul>
24. 24. Internal Validity Threats in Experimental Research <ul><li>To what extent extraneous variables are being controlled by researcher. </li></ul><ul><li>If extraneous variables are not controlled, the researcher is not certain that the affected change on the experimental group is caused by the treatment or the extraneous variable. </li></ul>
25. 25. Experimental Research <ul><li>CONTROL: </li></ul><ul><li>nonrandomized control group pretest-posttest </li></ul><ul><li>(Quasi) E O 1 X O 2 C o 1 o 2 </li></ul>
26. 26. Extraneous Variables Threatening Experimental Research <ul><li>History </li></ul><ul><li>Maturation processes </li></ul><ul><li>Pretesting procedures </li></ul><ul><li>Measuring instruments </li></ul><ul><li>Statistical regression </li></ul><ul><li>Differential selection of subjects </li></ul><ul><li>Experimental mortality </li></ul><ul><li>Interaction of selection and maturation </li></ul>
27. 27. Extraneous Variables Threatening Experimental Research <ul><li>Interaction of selection & x </li></ul><ul><li>Interaction of pretesting & x </li></ul><ul><li>Reactive experimental procedures </li></ul><ul><li>Multiple-treatment interference </li></ul>
28. 28. Extraneous Variables Threatening Experimental Research <ul><li>History </li></ul><ul><ul><li>Situation/event other than treatment may occur between the first and second measurement. </li></ul></ul><ul><li>Maturation Processes </li></ul><ul><ul><li>Changes (biological/psychological) which may occur to the subjects at the right time. </li></ul></ul><ul><li>Pretesting Procedures </li></ul><ul><ul><li>Answering the pretest before treatment may interfere with subject’s performance in the posttest. </li></ul></ul>
29. 29. Extraneous Variables Threatening Experimental Research <ul><li>Measuring Instruments </li></ul><ul><ul><li>May be due to instruments that are not reliable; changes in instruments; changes in level of difficulty </li></ul></ul><ul><li>Statistical Regression </li></ul><ul><ul><li>May occur if students with extreme scores in the pretest regress towards the mean of the posttest even if without treatment </li></ul></ul>
30. 30. Extraneous Variables Threatening Experimental Research <ul><li>Differential Selection of Subjects </li></ul><ul><ul><li>Important differences had existed between the e group and the c group even before the treatment was administered </li></ul></ul><ul><li>Experimental Mortality </li></ul><ul><ul><li>Reduction in number due to drop outs </li></ul></ul><ul><li>Selection-Maturation Interaction </li></ul><ul><ul><li>Preexisting maturation undetected during selection especially in intact groups </li></ul></ul>
31. 31. Extraneous Variables Threatening Experimental Research <ul><ul><li>Experimenter Bias </li></ul></ul><ul><ul><ul><li>Unintentional effects that the researcher has on the study </li></ul></ul></ul><ul><ul><li>Hawthorne Effect </li></ul></ul><ul><ul><ul><li>Subject effects </li></ul></ul></ul><ul><ul><li>Henry Effect </li></ul></ul><ul><ul><ul><li>Control group knowing they are being experimented on exerting extra effort and performing above expected average </li></ul></ul></ul>