Question

in hypothesis testing, what role does the alternative hypothesis play?
a. it proposes a significant effect or difference that is tested against the null hypothesis
b. it serves as the default position that there is no effect or difference
c. it is assumed to be true until proven otherwise
d. it is used to calculate the p - value

Explanation:

In hypothesis testing, the alternative hypothesis ($H_a$) is what we might believe if the null hypothesis ($H_0$) is rejected. It represents a claim of a significant effect or difference. The null hypothesis ($H_0$) is the default position of no effect or difference (so option b is for the null hypothesis), and the null is assumed true until evidence suggests otherwise (so option c is for the null). The p - value is calculated under the assumption that the null hypothesis is true (so option d is incorrect).

Answer:

A. It proposes a significant effect or difference that is tested against the null hypothesis