A study was conducted to examine the impact of speaking in public on college students. A class of 15 statistics students participated in the study. At the beginning of a lecture the students recorded their systolic blood pressure. During the lecture the instructor called on each student to stand and answer questions about topics in the lecture. After speaking the students once again recorded their blood pressure. The resulting values are given below along with summary statistics. before 115 123 128 125 136 108 130 113 105 136 146 138 108 149 132 after 141 142 146 136 144 111 132 114 103 133 140 130 100 133 113 difference -26 -19 -18 -11 -8 -3 -2
A study was conducted to examine the impact of speaking in public on college students. A class of 15 statistics students participated in the study. At the beginning of a lecture the students recorded their systolic blood pressure. During the lecture the instructor called on each student to stand and answer questions about topics in the lecture. After speaking the students once again recorded their blood pressure. The resulting values are given below along with summary statistics.
| before | 115 | 123 | 128 | 125 | 136 | 108 | 130 | 113 | 105 | 136 | 146 | 138 | 108 | 149 | 132 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| after | 141 | 142 | 146 | 136 | 144 | 111 | 132 | 114 | 103 | 133 | 140 | 130 | 100 | 133 | 113 |
| difference | -26 | -19 | -18 | -11 | -8 | -3 | -2 | -1 | 2 | 3 | 6 | 8 | 8 | 16 | 19 |
| before | after | difference | |
|---|---|---|---|
| mean | 126.1 | 127.9 | -1.733 |
| st dev | 13.93 | 15.45 | 12.84 |
Does this information indicate that blood pressure increased because of speaking? Conduct an appropriate hypothesis test and show appropriate steps.
Let μ1 mean systolic blood pressure before speaking in public, and μ2 mean systolic blood pressure after speaking in public. The hypothesis for this test are:
Fill in the blank: This is a two sample t-test.
The statistic for this test is t = (to three places after the decimal),
and the p-value is (to three places after the decimal),
There sufficient statistical evidence, at the 5% level, to indicate that blood pressure increased because of public speaking.
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