Number of unrelated case-control samples needed, in addition to a fixed, mixed sample of nuclear and extended pedigrees, to achieve a power of 86 per cent under a model with 50 per cent additive and 50 per cent dominance variance (Add = Dom), assuming an allele frequency of 0.1. Values were generated for samples that comprised 30 per cent nuclear families and 70 per cent extended pedigrees, 50 per cent and 50 per cent, and 30 per cent and 70 per cent, respectively.