Research Design in Occupational Education


MODULE S2 CORRELATION
Statistical correlation refers to a quantifiable relationship between two variables. Furthermore, it is a measure of the strength and direction of that relationship. Two measures for each subject (or object) in the group are required. Pearson Product Moment Correlation Negative Correlation
y x
Positive Correlation
y x
Zero Correlation
y x
Moderate Positive Correlation
y x
Correlation Pounds of Nitrogen (x) Bushels of Corn(y)
Steps for Hypothesis Testing
Assumptions: (Same for Correlation and Regression)
According to Popham (1973, p. 80), "multiple correlation describes the degree of relationship between a variable and two or more variables considered simultaneously. . . . partial correlation allows the statistician to describe the relationship between two variables after controlling or partialing out the confounding relationship of another variable(s)." Four Special Correlation Methods and Variable Relationships Assessed
The correlation ratio (eta) is the method to used when the relationship is nonlinear.
5. State the null hypothesis for the above relationship. 6. Test the statistical significance of the calculated correlation coefficient and the effect on the hypothesis for the above relationship. 7. State the assumptions required for Pearson Product Moment Correlation. 8. Describe multiple correlation. 9. Describe partial correlation. 10. Name four special correlation methods and variable relationships assessed. 11. Name the correlation method used when the relationship is nonlinear. 