Practice question · Sort into groups
Sort each research hypothesis by whether it calls for a one-tailed or a two-tailed test.
Groups: One-tailed test · Two-tailed test
- The new drug will CHANGE anxiety, in some direction
- The new drug will REDUCE anxiety
- The two groups will DIFFER, we do not predict which way
- Group A will score HIGHER than group B
Hints
- A directional prediction (higher, lower, reduce) points to one tail; a non-directional one splits both tails.
- If the hypothesis names a direction, it is one-tailed; if it only says 'different' or 'changed', it is two-tailed.
Show the answer
One-tailed test: The new drug will REDUCE anxiety, Group A will score HIGHER than group B
Two-tailed test: The new drug will CHANGE anxiety, in some direction, The two groups will DIFFER, we do not predict which way
Why
Directional predictions ('reduce', 'higher') place the whole rejection region in one tail; non-directional predictions ('change', 'differ') split it across both tails. The two-tailed test is more conservative because it demands a more extreme result in the relevant direction.
Practise Hypothesis Testing and P-Values
The app has 7 more questions on this lesson, and keeps your place in the course. Psychology I is free to start.