Table 1. Frequencies of reviewed study characteristics.
| Signal type | Frequency |
|---|---|
| Event-contingent | 6 |
| Signal-contingent | 13 |
| Time-contingent | 4 |
| Mixed | 23 |
| Could not be determined | 0 |
| Sampling frequency* | |
| 1/day | 1 |
| 3/day | 3 |
| 4/day | 9 |
| 5/day | 3 |
| 6/day | 2 |
| 7/day | 1 |
| 8/day | 1 |
| 9/day | 2 |
| Mixed | 11 |
| Could not be determined | 2 |
| Sampling period | |
| 1 day | 1 |
| 4 days | 1 |
| 6 days | 1 |
| 7 days | 13 |
| 8 days | 2 |
| 10 days | 2 |
| 14 days | 11 |
| 16 days | 4 |
| 21 days | 4 |
| 28 days | 2 |
| ≥ 30 days | 1 |
| Mixed | 4 |
| Could not be determined | 0 |
| Response format | |
| Continuous numerical | 5 |
| Free response | 1 |
| Categorical | 1 |
| Likert type scale | 15 |
| Mixed | 22 |
| Could not be determined | 2 |
This table excludes review studies; Mixed = a combination of the categories was used.
*Sampling frequency only represents the frequency of surveys initiated by the study (i.e., signal- and time-contingent surveys)