Understanding Society User Support

Dear all,

I would like to ask what is the difference in the health condition variables in the main respondents file across the waves.

I am using information from waves 1,2 & 3. What I know so far is that, for example, the variable regarding asthma "a_hcond1" (wave 1) is repeated in wave 3 as well. However, in wave 2 there is this "b_hcondn1" variable again for asthma which also exists in wave 3. So it seems that for the health conditions in wave 3 we have two different sets of variables.

My question is what is the difference between these variables? I know that in wave 2 and 3 new respondents are introduced, so perhaps these two different variables for the same condition are related to the different respondents that took part in?