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Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board. 18 AP® STATISTICS
2002 SCORING GUIDELINES (Form B)
Question 6 (cont’d.)
Part 3: Correct mechanics, including the value of the test statistic, df, and P-value (or
rejection region). 1990
t = -.751 N
1.37 df = 396 SE Mean
0.097 P-value = .453 (or based on tables P-value > .20) Also OK to use conservative df of 199
Calculator using sample statistics:
t = .7515, P-value = .4527, df = 396.57
Calculator using raw data
t = .7512, P-value = .4529, df = 396.67
use a confidence interval approach:
Difference = mu 1990 - mu 2000
Estimate for difference: -0.100
90 percent CI for difference: (-0.319, 0.119)
use a “pooled” procedure
t = -.751
df = 398
if use rejection region, t.05 = + 1.660
Part 4: States a correct conclusion in the context of the problem, linking to the result of
the statistical test.
Because the P-value > α, fail to reject H0. There is not convincing evidence that the...
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