Understanding Society User Support

Hi there,

I am taking values of ficode from the income file, and want to attach them to the associated household file hhresp using a join by hidp.

Across waves f to l I have 4111 unique values of hidp from the income file. When I link to hhresp using hidp I find that 119/4111 (2.9%) do not link: that is, the hidp in income doesn't occur in the hhresp file. The proportion where the hidp is not present in hhresp varies across the seven waves I am looking at.

I have looked in detail for one hidp in wave j. That hidp occurs in the income, egoalt and indresp files, with a total of four pidps living at that household. But the hidp doesn't appear in hhresp.

What is going on?!

Thank you!
Chris