A professor gives an exam to a class with four recitation sections. Each section has 7 students. The professor has no reason to assume that the exam scores would not be independent and normally distributed with equal variance. However, it is unknown whether or not the section choice (different TAs and different days of the week) has any relationship with how students performed on the test. The professor conducts a one-way ANOVA, and finds that Ho should be rejected at a significance level of a = 0.01.

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A professor gives an exam to a class with four recitation sections. Each section has 7 students. The
professor has no reason to assume that the exam scores would not be independent and normally distributed
with equal variance. However, it is unknown whether or not the section choice (different TAs and different
days of the week) has any relationship with how students performed on the test. The professor conducts a
one-way ANOVA, and finds that Ho should be rejected at a significance level of a
0.01.
Source
SS
df
MS
F-ratio P-value
Between
1889.293
3
629.764
5.257 0.0062
Within
2875.271 24
119.803
As shown above, the professor finds that F(3,24)
occurring randomly. Additionally, the error variance was estimated as MSw = 119.803, and the sample
means for each group were obtained as shown in the table below.
= 5.257, which has a probability of p = 0.0062 of
Level
Mean
Group-1
Group-2
Group-3
Group-4
88.214
87.657
69.314
74.557
The professor decides to use the Tukey HSD method to test all possible pairwise contrasts. To do so, the
following table of q; statistics needs to be completed. For this presentation, the groups will be ordered
from smallest to largest means. (In other words, Group A should be the group with the smallest mean.)
First, indicate the appropriate order for the groups (use the group number). Then fill in the table with
values rounded to 3 decimal places. (Furthermore, even though the sign does not matter, report all
comparison statistics as positive values.)
(Note: we often create a table of differences and compare those to HSD. In this case, we need a table of q
statistics, which we will compare to qcritical)
Transcribed Image Text:A professor gives an exam to a class with four recitation sections. Each section has 7 students. The professor has no reason to assume that the exam scores would not be independent and normally distributed with equal variance. However, it is unknown whether or not the section choice (different TAs and different days of the week) has any relationship with how students performed on the test. The professor conducts a one-way ANOVA, and finds that Ho should be rejected at a significance level of a 0.01. Source SS df MS F-ratio P-value Between 1889.293 3 629.764 5.257 0.0062 Within 2875.271 24 119.803 As shown above, the professor finds that F(3,24) occurring randomly. Additionally, the error variance was estimated as MSw = 119.803, and the sample means for each group were obtained as shown in the table below. = 5.257, which has a probability of p = 0.0062 of Level Mean Group-1 Group-2 Group-3 Group-4 88.214 87.657 69.314 74.557 The professor decides to use the Tukey HSD method to test all possible pairwise contrasts. To do so, the following table of q; statistics needs to be completed. For this presentation, the groups will be ordered from smallest to largest means. (In other words, Group A should be the group with the smallest mean.) First, indicate the appropriate order for the groups (use the group number). Then fill in the table with values rounded to 3 decimal places. (Furthermore, even though the sign does not matter, report all comparison statistics as positive values.) (Note: we often create a table of differences and compare those to HSD. In this case, we need a table of q statistics, which we will compare to qcritical)
Comparison Groups
Groups
(ascending order)
Group A
Group B
Group C
Group D
Group A = 3
%3D
Group B = 4
Group C =
Group D =
1
What is the critical value of the studentized range for the Tukey HSD test (a
0.01)?
Acrit
Mark all pairwise comparisons that are statistically significant
group A vs. group
В
group A vs. group C
group A vs. group D
group B vs. group C
Ogroup B vs. group D
group
C vs. group D
none of the groups are statistically significantly different
Transcribed Image Text:Comparison Groups Groups (ascending order) Group A Group B Group C Group D Group A = 3 %3D Group B = 4 Group C = Group D = 1 What is the critical value of the studentized range for the Tukey HSD test (a 0.01)? Acrit Mark all pairwise comparisons that are statistically significant group A vs. group В group A vs. group C group A vs. group D group B vs. group C Ogroup B vs. group D group C vs. group D none of the groups are statistically significantly different
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