Absentee rates - Friday vs Wednesday: We want to test whether or not more students are absent on Friday afternoon classes than on Wednesday afternoon classes. In a random sample of 302 students with Friday afternoon classes, 48 missed the class. In a different random sample of 307 students with Wednesday afternoon classes, 32 missed the class. The table below summarizes this information. The standard error (SE) is given to save calculation time if you are not using software.
Data Summary
total number | total number | Proportion | |
Day | of absences (x) | of students (n) | p̂ = (x/n) |
Friday | 48 | 302 | 0.15894 |
Wednesday | 32 | 307 | 0.10423 |
SE = 0.02738
The Test: Test the claim that the absentee rate on all Friday afternoon classes is greater than the absentee rate on all Wednesday afternoon classes. Use a 0.05 significance level.
(a) Letting p̂1 be the absentee rate from the sample on Friday and p̂2 be the rate from Wednesday, calculate the test statistic using software or the formulaz =
(p̂1 − p̂2) − δp |
SE |
where δp is the hypothesized
difference in proportions from the null hypothesis and the standard
error (SE) given with the data. Round your answer
to 2 decimal places.
z =
To account for hand calculations -vs- software, your answer
must be within 0.01 of the true answer.
(b) Use software or the z-table to get the P-value of the test
statistic. Round to 4 decimal places.
P-value =
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