T or F? A two-sided alternative hypothesis, states that the parameter is different from the null value (it could be either greater than or less than).

Answer 1

This is true.

Reminder that a null hypothesis argues that there is no difference between the parameter and the null value.

A one-tail test seeks to only look at one direction- either that the parameter is significantly greater than the null value or that it is significantly less than the null value. But not both! It wants to reject the null hypothesis because it proposes that there is a specific direction it is going.

A two-tail test just wants to argue that the parameter is different, so it looks at both sides of a distribution (or the tails). In order to reject the null hypothesis, you want the parameter to fall in either tail (whereas in one-tail, it should fall in a specific tail- either the tail located on the greater side of the null or the lower).