Question

Opinions about whether caffeine enhances test performance differ. You design a study to test the impact of drinks with different caffeine contents on students' test-taking abilities. You choose 21 students at random from your introductory psychology course to participate in your study. You randomly assign each student to one of three drinks, each with a different caffeine concentration, such that there are seven students assigned to each drink. You then give each of them a plain capsule containing the precise quantity of caffeine that would be consumed in their designated drink and have them take an arithmetic test 15 minutes later. The students receive the following arithmetic test scores: Cola Coffee Black Tea Caffeine Content (mg/oz) 2.9 5.9 13.4 EX2 147,641 85 85 92 86 G 1,755 89 87 82 82 N 21 80 75 75 89 k 3 66 88 96 78 76 83 87 82 92 Ti 559 T2 577 T3 619 SS, 338.86 SS2 177.71 sS3 185.71 n2 7 n3 7 n 7 M 79.8571 M2 82.4286 M3 88.4286 You plan to use an ANOVA to test the impact of drinks with different caffeine contents on students' test-taking abilities. What is the null hypothesis? O The population mean test score for the cola population is different from the population mean test score for the black tea population. O The population mean test scores for all three treatments are not all equal. The population mean test scores for all three treatments are different. The population mean test scores for all three treatments are equal.

Answer 1

the population mean test score for all three treatments are equal

from given data:

	SS	df	MS
Between	265.86	2	132.93
within	707.28	18	39.29
total	973.14	20

F= variance between groups/Variance between groups

F =132.93/39.29

thus :F =3.38

You can not reject the null hypothesis. you do not have enough evidence,,,,,,,,,,,,,,