A sleep researcher conducts an experiment to determine whether sleep loss affects the ability to maintain sustained attention. Fifteen individuals are randomly divided into the following three groups of five subjects each: group 1, which gets the normal amount of sleep (7-8 hours); group 2, which is sleep-deprived for 24 hours; and group 3, which is sleep-deprived for 48 hours. All three groups are tested on the same auditory vigilance task. Subjects are presented with half-second tones spaced at irregular intervals over a 1-hour duration. Occasionally, one of the tones is slightly shorter than the rest. The subject's task is to detect the shorter tones. Note: These data are not exactly the same as in the textbook.

The following percentages of correct detections were observed:

SUM ST DEV

Normal Normal Sleep Sleep ^2

85 7225 83 6889 76 5776 64 4096 73 5329 381 29315

8.4083292 1257.25

Sleep-Deprived for 24 Hours 72 54 66 52 74 318 10.139

Sleep-Deprived for 24 Hours^2 5184 2916 4356 2704 5476 20636 1272.88

Sleep-Deprived for 48 Hours 60 56 66 58 69 309 5.49545

Sleep-Deprived for 48 Hours^2 3600 3136 4356 3364 4761 19217 688.155

a. Determine whether there is an overall effect for sleep deprivation.

b. Determine the size of effect, using .

2 c. Determine the size of effect, using .

d. Explain the difference in answers between part b and part c.

e. Do a planned comparison between the means of the 48-hour sleep-deprived group and the normal sleep group to see whether these conditions differ in their effect on the ability to maintain sustained attention. What do you conclude?

f. Do a post hoc comparisons, comparing the 48-hour sleep-deprived group and the normal sleep group using the Tukey HSD test. What do you conclude? Compare your answers to parts e and f. Explain any difference.

g. Same as part f, but use the Scheffe test.