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In: Statistics and Probability

1) In a study of the effects of caffeine on alertness, 32 subjects were randomly assigned...

1) In a study of the effects of caffeine on alertness, 32 subjects were randomly assigned to four groups. These groups were C1: wait-list control (no treatment), C2: placebo control, E1: experimental group 1 (mild caffeine treatment) and E2: experimental groups 2 (high caffeine treatment). Several subjects were not able to complete the study, reducing the group n’s to 7, 5, 6, and 3, respectively. The dependent variable scores were performance scores on a visual-motor task requiring alertness. The results are as follows: C1 C2 E1 E2 18 20 16 18 15 15 14 12 17 13 10 14 12 10 11 25 32 22 26 19 20 Do the results indicate a significant difference between treatment groups? State the null hypothesis, Fcritical, η2, and use Scheffe’s test to determine which treatment conditions differ in the event of rejecting the null hypothesis. Conclude with a summary appropriate for publication.

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