Below are matched pair data consisting of driving test scores
for a sample of 11 licensed drivers before and after they took an
online traffic safety class. At a 0.05 significance level, use the
sign test to test the claim that taking this online class affects
driving test scores.
Before | 31 | 44 | 40 | 50 | 53 | 48 | 59 | 31 | 38 | 58 | 55 |
---|---|---|---|---|---|---|---|---|---|---|---|
After | 31 | 47 | 41 | 48 | 52 | 52 | 55 | 35 | 37 | 59 | 55 |
(a) What is the value of the test statistic used in this sign
test?
(b) What is the critical value in this sign test?
(c) What is the correct conclusion of this sign test?
Answer:
provided information
Null and Alternative Hypotheses:
Ho: Median of Differences = 0
Ha: Median of Differences > 0
a)test statistics:
Differences between( Before-After)
0
-3
-1
2
1
-4
4
-4
1
-1
0
Positive sign count (x+)= 4
Negative sign count(x-) = 5
Total count = 9
The test statistic is X = min{X+, X-}
X= min{4, 5}= 4
b)critical value:
The critical value for the signficance level provided and the type of tail is X* = 1
(c) Decision rule:
Accepted Ho, because X>X*
There is not sufficient evidence to support claim that the online class affects driving test scores.
Thank you!
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