In a study comparing the systolic blood pressure of individuals sitting and standing, 10 subjects had their blood pressure measured in the two conditions. The investigator planned to test the hypothesis that the
Mean blood pressure readings are the same sitting and standing (the subjects remained in each position
For 5 minutes) . If the investigator tests at the 10% level of significance, the rejection region would be

Question

In a study comparing the systolic blood pressure of individuals sitting and standing, 10 subjects had their blood pressure measured in the two conditions. The investigator planned to test the hypothesis that the
Mean blood pressure readings are the same sitting and standing (the subjects remained in each position
For 5 minutes). If the investigator tests at the 10% level of significance, the rejection region would be 
A) $| t | > 1.734$
B) $\mathrm { t } < - 1.833$ or $\mathrm { t } > 1.8333$
C) $| t | > 1.725$
D) $\mathrm { t } > 1.8333$

Quizplus · Accepted Answer

Since the sample size is small (n = 10), we use the t-distribution. The level of significance is 10%, which corresponds to a two-tailed test with α/2 = 0.05. The degrees of freedom for the t-test are df = n - 1 = 9. Using a t-distribution table (or software), we find the critical values to be $\mathrm { t }_{0.05/2,9} = -1.833$ and $\mathrm { t }_{0.05/2,9} = 1.833$. Therefore, the rejection region is any t-value less than -1.833 or greater than 1.833. The absolute value of t should be used because the alternative hypothesis is two-tailed. Thus, the correct choice is B.

In a Study Comparing the Systolic Blood Pressure of Individuals ∣t∣>1.734| t | > 1.734∣t∣>1.734

In a Study Comparing the Systolic Blood Pressure of Individuals $| t | > 1.734$