Pearson and Spearman correlation
HW # 3
5. You should use a ______ correlation when one or more of the variables are measured on an ordinal scale.
c. Point biserial
d. Any of these are appropriate.
Answer: b. Spearman
10. A statistics instructor required students to complete homework assignments prior to their taking an online statistics exam. After the students took the exam, he wanted to create a regression equation using students' total homework points to predict their scores on the exam. The SPSS output is below, what is the regression equation for this prediction?
a. Y = .06 (X) + 4.21
b. Y = .727 (X) + 28.14
c. Y = .782 (X) + 28.14
d. Y = .727 (X) + 4.21
Answer: b. Y = .727 (X) + 28.14
12. In regression, the predictive contribution of each independent variable is represented by ______.
a. the partial slope
b. a β coefficient
c. the regression plane
d. a path coefficient
Answer: a. the partial slope
30. Which of these scatterplots is most likely to result in the regression equation Y′ = 2.25 – .45(X)?
a. Figure A
b. Figure B
c. Figure C
d. Figure D
Answer: b. Figure B
Spearman’s correlation coefficient is a measure to calculate the correlation between two Ordinal variables.
Coefficients are given in 3rd table “coefficients” under the heading unstandardized coefficients
Each partial coefficient gives the contribution of an independent variable in multiple regression.
In the first figure, the trend is increasing but the β coefficient is negative i.e. -0.45, but in the second figure the trend is decreasing which matches the requirement. Figure C represent increasing and decreasing trend both and Figure D is showing no trend at all.