A study was conducted to explore the effects of ethanol on sleep time. Fifteen r

Question

A study was conducted to explore the effects of ethanol on sleep time. Fifteen rats were randomized to one of three treatments. Treatment 1 got only water (control). Treatment 2 got 1g of ethanol per kg of body weight, and treatment 3 got 2g/kg of ethanol. The amount of REM sleep in a 24hr period was recorded, in minutes. Data are below:

Treatment 1: 63, 54, 69, 50, 72

Treatment 2: 45, 60, 40, 56

Treatment 3: 31, 40, 45, 25, 23, 28

(e) Create 95% CIs for all pairwise comparisons of means using the Tukey method. Do this by hand and show your work. You may use R to check your answers. Summarize your results using letter codes. What do you conclude?

(f) What would have been the multiplier if Fisher’s LSD method had been used? Bonferroni? Use a t table. You may check your answer in R. You do not need to make the complete CIs for this question, just give the values of the multipliers.

Explanation / Answer

e.

Minitab output for tukeys comparision :

One-way ANOVA: Treatment 1, Treatment 2, Treatment 3

Source DF SS MS F P
Factor 2 2457.0 1228.5 14.77 0.001
Error 12 998.0 83.2
Total 14 3454.9

S = 9.119 R-Sq = 71.12% R-Sq(adj) = 66.30%

Individual 95% CIs For Mean Based on
Pooled StDev
Level N Mean StDev +---------+---------+---------+---------
Treatment 1 5 61.600 9.450 (------*-------)
Treatment 2 4 50.250 9.323 (-------*-------)
Treatment 3 6 32.000 8.718 (------*-----)
+---------+---------+---------+---------
24 36 48 60

Pooled StDev = 9.119

Grouping Information Using Tukey Method

N Mean Grouping
Treatment 1 5 61.600 A
Treatment 2 4 50.250 A
Treatment 3 6 32.000 B

Means that do not share a letter are significantly different.

hope this will be helpful.

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