Question

Trying to learn Minitab and verify my answers from these questions in the workbook. Thank you in advance!

Students applying to law school must take the LSAT exam. Sicne competition gor acceptance is stiff, many students take a course that is advertised to boost scores on the LSAT. The agency that teaches the course claims the course is and effective way to raise scores on the LSAT. To test this claim, a group of students is given the LSAT and their scores are recorded. They then attend the course for 5 weeks and retake the exam. Their scores are recorded again. The pre and post test scores are as follows:

POSTSCORE PRESCORE

129 148

147 154

147 135

140 164

157 132

144 150

147 154

156 143

151 139

144 132

144 136

149 122

128 151

154 134

145 134

131 135

158 135

153 150

140 147

146 135

133 125

169 131

152 115

131 172

144 149

a.) Are the samples independent or dependent? Explain.

b.) What are the apporpriate null and alternative hypotheses for testing the claim that the course is an effective way to raise scores on the LSAT?

c.) What Minitab procedure are you going to use to test the hypotheses formulated above?

d.) Create the probability plot necessary to validate the procedure chosen above.

e.) Perform the appropriate test of hypotheses in Minitab and write the results of the session window output below.

f.) Obtain the 96% confidence interval to estimate the average difference between the pre-scores and post-scores

g.) What conclusion can you draw about the effectiveness of the LSAT preparation course? Explain.

Answer 1

a)

The samples are dependent.

Because prescore is obtain from the same sample post score is obtained.

b)

let

postscore=x

prescore=y

the null hypothesis

the alternative hypothesis

c)

1. Enter data
2. stat
3. basic statistics
4. paired t
5. select samples
6. options
7. select correct alternative and confidence level
8. ok
9. ok

d)

e)

output

f)

from above 96% lower confidence interval to estimate the average difference between the pre-scores and post-score is  -2.36

g)

as pvalue=0.118>significance level=0.04

we shall acept the null hypothesis.

and conclude that no significance difference between mean prescore and mean post score.

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THANK YOU.