kaks
A logical variable to indicate whether kaks is turn on or off, if kaks is TRUE, conditional kaks will be computed only among positive seelction sites, or if kaks is FALSE, conditional kaks will be computed only among all sites of sequence.
lod_cut
The LOD confidence score cutoff, the default value is 2. If lod is larger than 2, it means the positive selection of individual site or the conditional selection pressure among sites are significant.