timediffof[Qa,Qb]
Date/Time
Returns the difference in minutes between two time question responses (Qb − Qa). Used to measure interview duration by placing *TIME questions at the start and end of the questionnaire.
Parameters
| Parameter | Type | Description |
|---|---|---|
Qa |
Question ref | First time question (the earlier time) |
Qb |
Question ref | Second time question (the later time) |
Returns: Integer — difference in minutes (Qb minus Qa)
Examples
expressions
timediffof[Q15,Q16]>=10 -- interview lasted at least 10 minutes timediffof[Q15,Q16]<=60 -- interview under one hour timediffof[Q15,Q16]=0 -- both timestamps identical
Returns a positive integer when Qb is later than Qa. May return negative if times cross midnight.
Use in quality control to flag interviews completed too quickly (possible speeders).