Which statement is correct?

a. Matched pair designs can be used for any data as long as the two sample sizes are equal.

b. The matched pairs t test is robust against non‑normality as long as the standard deviation of the differences is large.

c. Matched pairs designs are preferred because they require fewer subjects.

d. The matched pairs t test is the same as the one‑sample t test but done on the differences.

Correct option is (a).

Step-by-step explanation:

The dependent t-test (also known as the paired t-test or matched-samples t-test) compares the two means associated groups to conclude if there is a statistically significant difference amid these two means.

We use the paired t-test if we have two measurements on the same item, person or thing. We should also use this test if we have two items that are being measured with a unique condition.

For instance, an experimenter tests the effect of a medicine on a group of patients before and after giving the doses.

Or in case of testing the level of reading comprehension of students before and after the speed-reading class we use t-test for dependent means.

The assumptions of paired t-test are:

The dependent variable that is tested should be continuous The observations are independent The dependent variable is normally distributed There should not be any outliers.

Since the data consists of matched pair, both the samples must be of the same size.

Thus, the correct option is (a).