Understanding Society User Support

Hello, I have been trying to calculate how the extra 5 minutes sample size changes from wave 1 to wave 3. Because the low density area identifier, gps comparison and ethnic minority boost identifiers aren’t available in subsequent waves indresp files, I merged these in to the later waves indresp files from wave 1. After having done this I have two questions:

1- Why do the totals of the LDA, GPS comparison and EMB samples add up to more than the extra 5 minutes sample total (using the extra 5 minutes identifier)? I found this to be the case for waves 1, 2 and 3.

2- The extra 5 minutes sample appears to gain participants in waves 2 and 3 who weren’t part of the sample in wave 1. For example, in wave 2 I found 6,223 extra 5 minutes sample members (but only 5,479 were from the original wave 1 sample). How did these new participants come to be included? (Apologies if this is detailed in a user guide somewhere, I have had a look but can’t seem to find the detail on this).

Any help on this would be very much appreciated

Many thanks

Natalie