How to Compare Two Waves of a Tracker in Different Data Files
In order to compare the results in two different waves of a tracker it is necessary to combine the two different waves into a single data file. The best way to do this is to extract a single data file from the data collection software, containing both waves of the tracker and a variable time-stamping the time of interviews.
Alternatively, it is possible to merge two data files together using Tools > Merge Data Files > Add New Cases, although this should in general be avoided as:
- It can be difficult to manually construct a Date variable.
- It can be difficult when questionnaires have changed between waves.
- It requires the person doing it to have a good understanding of data (as ill-considered decisions can have large ramifications).
Once the a single cumulative data file has been obtained, it is imported into Q using File > Data Sets > Update.
Finally, results between the waves are tested by selecting a variable indicating wave in the Brown Drop-down Menu.