An aerospace psychologist wanted to investigate whether cockpit background lighting affects target acquisition speed. To test this, they conducted an experiment where participants completed a simulated missile-targeting sequence.
One group of five military pilots completed the simulation in a cabin illuminated by monochromatic red tactical lighting. A second, independent group of five military pilots completed the same simulation under standard white cockpit lighting.
The target acquisition time (in seconds) was recorded. The data and their corresponding pooled ranks are shown in the table below:
| Red Light Cabin Group | White Light Cabin Group | ||||
|---|---|---|---|---|---|
| Participant | Time (s) | Rank | Participant | Time (s) | Rank |
| P1 | 4.2 | 3 | P6 | 3.1 | 1 |
| P2 | 5.8 | 6 | P7 | 4.0 | 2 |
| P3 | 6.1 | 7 | P8 | 4.5 | 4 |
| P4 | 7.5 | 9 | P9 | 5.0 | 5 |
| P5 | 8.0 | 10 | P10 | 6.5 | 8 |
| n1=5n_1 = 5n1=5 | n2=5n_2 = 5n2=5 |
Give one reason why the Mann-Whitney U test is the appropriate inferential test to use to analyse the data from this study.
