There are some sample members who have provided data from a combination of waves/instruments for which they have a weight of zero. This is not a mistake: these weights are zero for one of two reasons: there are zero weights by sample design, and there are zero weights as a result of fieldwork issuing rules.
Temporary Sample Members
Temporary Sample Members (TSMs) are not strictly part of the Understanding Society sample. Data are collected from these persons in order to provide contextual information regarding the sample members (OSMs). Consequently, all longitudinal weights will always be zero for all TSMs. For example, any TSMs who participated in Waves 6, 7 and 8 will have a zero value of h_indinui_lw, even though this weight is designed for longitudinal analysis starting at Wave 6.
Cross-sectional weights are not necessarily zero for TSMs, but there is a sub-set of TSMs for whom these weights too are always zero, as a consequence of the sample design. These people have zero design weights as well. They are ‘TSMs from Wave 1’ selected through the EMB and IEMB boosts. These are non-eligible people (e.g. white British) who are co-residents with eligible people (e.g. ethnic minorities or immigrants) at the first wave of sample selection. Their zero weights are correct and are related to the sample design. The sample design was implemented in the most cost efficient way to meet the need for analysing ethnic minorities, recent immigrants and the whole of UK population. Avoiding these zero weights would have had a substantial cost implication but would have added very little to the precision of estimates.
