Simulated unlinked trait. Spairs distribution for 1,000 datasets with a simulated unlinked trait and the real STRP data (solid symbols) and 1,000 true null datasets (open symbols). The 50th (squares) and 95th (circles) percentiles of the Spairs distributions at each STRP are shown. Numbers and tick markers on the top axis denote STRPs and their positions. Dotted lines indicate the 50th and 95th percentiles assuming a normally distributed score.