Understanding Society User Support

Hi there,

I'm constructing indicators relating to an individual's current employment in wave 8. My sub-sample consists of employees aged 25 to 60 who reported good self-rated health and no psychological distress in the previous wave.
The two indicators in question are
1. the relative pay level (using net labour income fimnlabnet_dv), and
2. pay volatility (whether there's a discrepancy between usual net pay in current (main) job (paynu_dv) and last net pay in current (main) job (payn_dv).

While the ratio of missing observations for relative pay level are low, that's not the case for pay volatility. The reason for that being that while fimnlabnet_dv (and one of its components, paynu_dv) is imputed, payn_dv isn't. Beyond the number of missing cases, I'm more concerned that pay volatility won't be missing at random as certain respondents might be more likely to refuse to answer questions on their pay (usual net pay and overall net labour income will be imputed for them but lay pay won't be). Could you confirm this? With your experience on the income variables, do you think it's safer to drop the indicator on pay volatility altogether? For the analysis I'm doing, it'd ideal if the assumption of missing at random could hold. I've read the UKHLS income data guidance but couldn't find information on non-response to income questions.
Thanks very much