Question

6. An educational psychologist studies the effect of frequent testing on retention of course material. In one of the professor's sections, students are given quizzes each week. The second section receives only two tests during the semester. At the end of the semester, both sections receive the same final exam, and the scores are summarized below. Do the data indicate that testing frequency had a significant effect on performance? Use a two-tailed test at the .01 level of significance.

Frequent Quizzes

n = 15

x ̅ = 82

s^2=7.07

Two Exams

n= 15

x ̅ = 78

s^2=13.57

Answer 1

The available data is shown in below, Frequent Quizzes Two Exams Sample Mean X = 82 I = 78 Sample Variance Sample Size S = 7.07 ) n =15 $3=13.57 n = 15 Null hypothesis, H.:/4 = 112 Alternative hypothesis, H:44 € 12 Level of significance, a = 0.01 Calculate the test statistic value. 1-12 t=- V ዜ ዜ2 82-78 17.07 13.57 V 15 15 = 3.41

Calculate the degrees of freedom. 2 n df =- n - 1 n ) n - n (7.07 13.57 15 * 15 1 (7.071 (13.57 15-1 15 15-1 15 = 25 +- Calculate the P-value P-value = (=TDIST(3.41,25,2)) (Use MS Excel function) = 0.00221103 = 0.0022 (Round to 4 decimal place) Decision: Reject H , because, P-value is less than the 0.01 level of significance. Conclusion: There is enough evidence to conclude that the data indicate that testing frequency had a significant effect on performance at the 0.01 level of significance.