Question:
A researcher wishes to learn if a certain drug affects the reaction time of pilots to air traffic control instructions. She obtained a sample of pilots and randomly divided them into two groups.
She then had one pilot group take the drug and used the second group as a control. Pilots were given headsets and given commands from an air traffic controller. The reactions times for each group of pilots is below.
The researcher is interested in learning if the drug reduces the reaction time.
Her hypothesis is: The mean reaction time in group A will be less than the mean in group B.
| Group A |
Group B |
Treated with Drug Control
|
Not Treated |
| 0.72 |
0.71 |
| 0.68 |
0.83 |
| 0.69 |
0.89 |
| 0.66 |
0.57 |
| 0.57 |
0.68 |
| 0.66 |
0.74 |
| 0.7 |
0.75 |
| 0.63 |
0.67 |
| 0.71 |
0.8 |
| 0.73 |
0.78 |
A t-test can be used to test the probability that the two means do not differ. The alternative is that the reaction times from the group treated with the drug will not be less than that from the control group.
This is a one-tailed test because the researcher is interested in if the drugdecreased reaction time. She is not interested in if the drugchanged reaction time.