An ergonomic psychologist investigated the impact of industrial warning designs on operator cognitive workload. They used an independent measures design to compare subjective mental workload ratings (from 0 to 16, where 0 = 'extremely low workload' and 16 = 'extremely high workload') of control room operators responding to either abstract auditory beeps or automated speech alerts during a simulated emergency scenario. Some of the data collected is presented in the table below.
| Cognitive workload ratings (0 to 16) under abstract beeps compared to speech alerts | Speech alerts | ||
|---|---|---|---|
| Abstract beeps | Speech alerts | ||
| Rating | Rank | Rating | Rank |
| 14 | 18 | 9 | 11 |
| 11 | 14.5 | 2 | 1 |
| 7 | 8 | 4 | 4 |
| 13 | 17 | 3 | 2.5 |
| 12 | 16 | 6 | 6.5 |
| 15 | 19 | 11 | 14.5 |
| 3 | 2.5 | 5 | 5 |
| 8 | 9.5 | 10 | 12.5 |
| 16 | 20 | 8 | 9.5 |
| 10 | 12.5 | 6 | 6.5 |
Explain what ranking the data means in the context of this study.
