Assignment 1 Correlation and Prediction_R3

Module 3 – Correlation and Prediction Use the following data to answer the questions 1 through 5. Enter the raw data below in SPSS (you do not have to save the file). Semester Grade Number of Absences 85 7 98 1 84 5 86 14 90 4 71 15 82 6 70 3 91 1 56 13 86 3 87 4 70 9 70 10 82 7 98 0 81 1 97 0 95 8 99 1 98 0 92 0 86 3 90 1 82 7 1) What is the mean and standard deviation (s) for semester grade variable? Answer ________ a. 86.00 ± 10.89 b. 85.04 ± 10.89 c. 86.00 ± 12.00 d. 85.04 ± 12.00 2) Run the correlation between the two variables. What is the correlation coefficient, r ? Answer ________ a. -.690 b. .219 c. -.379 d. .001 3) Draw a scatterplot figure illustrating the correlation that you found above. Label the figure.

4) What percentage of variation in semester grade accounted for by number of absences? (Hint: think Coefficient of Determination [CD]). Answer ________ a. 81 b. 48 c. 69 d. 95 5) Assume you were able to create an equation from the above data to predict semester grade from number of absences, but you want to have a “better” prediction equation. What two predictor variables might you add? For questions 6 - 8. Assume that you have helped George et al. (1993) to develop an equation for predicting VO 2max from 1.5-mile run time (in minutes). The correlation between 1.5-mile run time and VO 2max measured on a metabolic cart is .80. The equation that you have developed is: Predicted VO 2max = 79.31– 2.767 * run time Assume that the group on which you created this equation is described as follows: N = 400 Mean VO 2max = 47 ml kg ∙ -1 min ∙ -1 S of VO 2max = 5 ml kg ∙ -1 min ∙ -1 6) Assume that Pat’s 1.5-mile run time is 12 minutes and 30 seconds. What is Pat’s predicted VO 2max based on the run time? Answer ________ a. 47.50 b. 44.72 c. 57 d. 46.11 7) What is the Standard Error of Estimate (SEE) for predicting VO 2max from 1.5-mile run time? Answer ________ a. 25 b. 5 c. .25 d. 3 8) Assumed a normal distribution, what is the 95% confidence interval estimate for Pat’s actual VO 2max score? Use +/- 2 standard error of estimate (SEE) in the calculation and provide upper and lower bound scores (i.e., between two scores).