Error detection using blocks. Plots generated using the imageplot function. A) The last individual is wrongly assigned to the family group (excessive number of short recombinations). Note that the inclusion of a wrong individual causes problems with block assignment for the whole family (compare the block structure for the same group in Figure 3). Data shown is for bovine chromosome 29 with 8 half-sib and an unrelated individual intentionally included. B) Putative map error on chromosome 1. A map error has a cumulative effect and causes problems downstream evidenced by chromosome blocks consistently breaking across all individuals.