Aresearcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. a sample of n = 9 college students is obtained and each student’s performance on a familiar video game is measured before and after eating a traditional dinner including roast turkey. the average score dropped by m = 14 points after the meal with ss = 1152 for the difference scores.

a. is there is significant difference in performance before eating versus after eating? use a two-tailed test with α = .05.

b. compute r2 to measure the size of the effect.

c. write a sentence demonstrating how the outcome of the test and the measure of effect size would appear in a research report.