Table 2. LRT tests for HA1 sequences of human A(H1N1) influenza viruses.
| LRT (M2a − M1a) (2Δl) (p-values)1 | LRT (M8 − M7) (2Δl) (p-values)1 | LRT (M8 − M8a) (2Δl) (p-values)2 | |
| I-i 1918∼1919 (5 strains) | 3.44 (0.1791) | 3.46 (0.1773) | 3.44 (0.0318) |
| I-ii 1979∼2000 (45 strains) | 0 | 0 | 0 |
| I-iii 2000∼2001 (22 strains) | 2.98 (0.2254) | 2.84 (0.2417) | 2.96 (0.0427) |
| I-iv 2001∼2007 (89 strains) | 1.86 (0.3946) | 0.34 (0.8437) | 1.16 (0.1407) |
| I-v 2006∼2008 (100 strains) | 62.42 (0.0000) | 65.32 (0.0000) | 61.70 (0.0000) |
| II 2007∼2009 (74 strains) | 0.78 (0.6771) | 0.80 (0.6703) | 2.44 (0.0591) |
1
We used the degree of freedom of 2 for these LRT tests that is expected to be too conservative. 2 The p-values were calculated from χ2 distribution using degree of freedom of 1 that was then divided by a factor of 2 for the mixture distribution, as suggested by the author of PAML 4.0.