Fig. 2.

Expected value and bias in the identified number of parental genotypes when the true number of parental genotypes is known. The identified number of parental genotypes by sibship reconstruction is denoted n with expected value E(n) derived from the unique items distribution. The true number of parental genotypes (the fecund female worm burden) is denoted N and the number of sampled miracidial offspring m, increasing from 5 to 40 per host, from light to dark blue. The dashed line in panel a corresponds to the relationship E(n) = N, indicating an unbiased estimate of N. In panel b the bias is expressed as a percentage underestimate of N, [E(n) − N]/N which is plotted against the ratio m/N. The horizontal dashed line in panel b indicates a 5% underestimate; the vertical dashed line is plotted at m/N = 3, the approximate ratio above which n is an underestimate of less than 5%