A random sample of nurses working night shifts were asked whether they were fatigued (no or yes) and what form of sleep aid they used. Assume that each person used one sleep aid. The table shows the results.
a. Why is a chi-square test for independence inappropriate for this data set?
b. Combine some groups. Put those who used a Dark Room or White Noise (natural) in one group, and in the other group (chemical) include all the others. Show the new table.
c. Using the table for part b, test the hypothesis that fatigue and form of sleep aid are independent at the 0.05 level.
d. Does this show that sleep aids cause fatigue?

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Options Contingency table resuts Rons: vart Coluins: None Cel format Expected count cohl DarkRoom OverTheCounter SileepAid Prescriptian SleepAid wteNoise T No 20 (14) (12.23) (11-51) 35 (29.49) 41 632 282 114 1O 3.6 (28.77) 719) (12.95) Total40 10 Chi-Square test Statistic DFValue p-value Chi-square 19.29373 0.0007 warning over 20% or cels have an expected count less than CheSquare siuspect