Median Mean Std Minimum Maximum ΣD(H1N1, H3N2)           Observed 1223 1223.06 7.2033 1183 1268 Predicted 1223 1223.01 18.536 1130 1305 ΣD(H1N1, H6N1)           Observed 883 884.128 6.4552 861 932 Predicted 884 884.109 20.6254 785 984 ΣD(H3N2, H6N1)           Observed 1243 1243.92 6.6514 1216 1277 Predicted 1244 1243.92 18.2835 1157 1331

Table 1: Hamming Distances Summed Over the 1701 Nucleotide Positions ofthe Hemagglutinin Gene. Influenza A subtypes of the paired gene sequences ofthe sequence datasets are identified in parentheses. The predicted values were obtained from 1×106 pseudorandom Bernoulli binomial trials.