Because ABSOLUTE could not distinguish between ploidy 2N and 4N in cases with no observed SCNAs, we discarded such non-aberrant samples from our analysis (Fig. 3a). For many tumor types, such cases were rare, due to the tendency for chromosomal losses following doubling (Fig. 3c, Fig. 6a,b, Supplementary Fig. 9). The representation of specific cancer subtypes may be biased by differences in ascertainment, however.
