Typical graphical output of fitTetra. Upper panel: histogram of the signal ratios: allele a/(allele a + allele b) of a set of tetraploid potato varieties (white bars) and a diploid cross progeny (gray bars) for marker PotSNP016. The model fitted to the tetraploid varieties is indicated (green line). Lower panel: the genotype (0 to 4 for nulliplex to quadruplex) assigned to the tetraploid samples in relation to the signal ratios. Unassigned samples are shown at the bottom in red. The diploid samples coincide with the nulliplex, duplex and quadruplex peaks of the tetraploid samples.