Table 5 Comparison of exact and IBS methods in a particular case

Genotype data Exact calculation IBS method Ratio LR1/LR2
Marker Sib1 Sib2 Genotype combination (1) Allele frequencies (2) Likelihood ratio (3) Shared alleles H (4) Likelihood ratio (5)
CSF1PO 9–13 9–13 4 p9 = 0.044 p13 = 0.062 50.93 2   3.52 14.5
FGA 20–24.2 20–24.2 4 p20 = 0.156 p24.2 = 0.009 103.97 2   9.78 10.6
FES 12–13 12–13 4 p12 = 0.266 p13 = 0.047 13.38 2   2.94 4.6
F13A1 5–5 5–5 1 p5 = 0.184   10.32 2   3.83 2.7
D19S253 8–12 12–12 2 p12 = 0.369   0.93 1 0.760 0.35 2.7
F13B 6–8 6–10 6 p6 = 0.080   1.81 1   0.86 2.1
LPL 10–12 10–10 2 p10 = 0.275   1.16 1 0.723 0.89 1.3
TH01 9.3–9.3 9–9.3 2 p9.3 = 0.241   1.29 1   1.02 1.3
D18S51 13–19 14–17 7    0.25 0   0.25 1.0
D8S1179 13–15 13–15 4 p13 = 0.344 p15 = 0.116 4.82 2   6.07 0.8
TPOX 8–11 8–10 6 p8 = 0.512   0.49 1   0.78 0.6
VWA 17–18 17–18 4 p17 = 0.275 p18 = 0.206 3.52 2   5.71 0.6
D21S11 63–67 63–65 6 p63 = 0.244   0.76 1   1.17 0.6
Cumulative log(LR)       6.47    2.92
Probability       >99.999%    99.9%
1. Calculations applied to the most discordant pair from Fig. 2 are fully displayed. (1)from Table 1A; (2)calculated from full-sib sample data; (3)FS rather than NR, computed using formulas from Table 1A; (4)computed from sample data; (5)FS rather than NR, computed from values in Table 3 or applying formulas from Table 2 to the displayed H values.