In order to simplify the relationship between power and tumor purity/ploidy for presentation in Supplementary Fig. 7, we considered the detection power of the expected locus, over the genome-wide copy average. Power as such is determined by the sample allelic index δτ = α/D, which is solely a function of tumor purity/ploidy (eqn. 1). Expected power is obtained by using allelic fraction f =δτ in eq. (9). This calculation differs only in the substitution of expected genomic copy-number, i.e. ploidy (τ)for the local copy-number qt in eq: (10).
