12.2 The effect of caffeine levels on performing a simple finger tapping task was investi- gated in a double blind study. Thirty male college students were trained in finger tapping and randomly assigned to receive three different doses of caffeine (0, 100, or 200 mg) with 10 students per dose group. Two hours following the caffeine treatment, students were asked to finger tap and the numbers of taps per minute were counted. 14 The data are tabulated below. Caffeine Dose Finger Taps per Minute 0 mg 100 mg 200 mg 242 245 244 248 247 248 242 244 246 242 248 246 245 247 248 250 247 246 243 244 246 248 250 252 248 250 246 248 245 250 (a) Make side-by-side box plots for the three groups. Do these plots indicate any obvious differences between the groups? (b) Construct an ANOVA table and test whether there are significant differences in finger tapping between the students treated with different doses of caffeine. Use a = .10. Interpret your results. (c) Check the normality and constant variance assumptions by making residual plots.