Hi Raffaele,
I would like to make a difference between outcome variables between the wave seven and the wave nine, in this regard, if in the wave 7 (2015-2017) a parent is interviewed in the month X of the year 2017 about his/her child's health status, in the wave 9 (2017-2019) can the same parent be interviewed in the month Y (different from the month X) of the year 2017 about his/her child's health?
We aim to interview households and individuals at approximately one-year intervals. This means we start the interviewing process in specific months, recorded in the w_month variable, which remains relatively stable across waves. If there is any shift in the planned month of the interview, it’s typically to an adjacent month. You can verify this by cross-tabulating g_month with i_month.
The period covered by g_month runs from January 2015 (jan yr1) to December 2016 (dec yr2). Thus, interviews conducted later, such as in January 2017 (as you mentioned), actually began with fieldwork scheduled earlier (again, recorded in g_month). For example, if g_month is December 2016 (dec yr2), then i_month for most households and respondents would also be around December, but in 2018 (i_month=dec yr2).
Therefore, you should not see any cases where a parent is interviewed in month X of 2017 about their child's health status in wave 7 and then again in 2017 in wave 9. If such instances occurred, it would be due to errors or specific issues during fieldwork. However, no such cases exist in the scenario you are investigating.
Or in the wave 7, as the same parent was interviewed in the month X of the year 2017 about his/her child's health status, in the wave 9 he cannot be interviewed in the year 2017, but he can be interviewed only in the year 2018 or 2019?
For the reasons stipulated above, this is highly unlikely.
If you want to test any other specific scenarios, I encourage you to download the data (I'm afraid data analysis for UKHLS data users is beyond our remit):
https://beta.ukdataservice.ac.uk/datacatalogue/studies/study?id=6614
You may also find our workshops useful:
https://www.understandingsociety.ac.uk/help/training/intro-to-understanding-society/
https://www.understandingsociety.ac.uk/help/training/introduction-to-understanding-society-self-paced-moodle/
Best wishes,
Piotr Marzec
UKHLS User Support
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