To examine the effect of caffeine on blood pressure, a researcher randomly selec

Question

To examine the effect of caffeine on blood pressure, a researcher randomly selects a sample of n = 30 NSC students and compares their blood pressure before and after drinking 6 oz. of black coffee. After drinking the coffee, systolic and diastolic blood pressure increased by an average of 2.4 points. Which statistical analysis should be used to determine if caffeine significantly increases blood pressure? a. z-test for sample mean b. z-test for single score c. t-test for single sample d. t-test for related samples

Explanation / Answer

Solution:- d) t- test for related samples.

The paired t-test calculates the difference within each before-and-after pair of measurements, determines the mean of these changes, and reports whether this mean of the differences is statistically significant.

A paired t-test can be more powerful than a 2-sample t-test because the latter includes additional variation occurring from the independence of the observations. A paired t-test is not subject to this variation because the paired observations are dependent. Also, a paired t-test does not require both samples to have equal variance.

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