Correlation () versus partial correlation () coefficients of concurrent substitutions between sites.

OTUs connected to their parent nodes with branches shorter than the threshold value are removed from each Pfam full alignment, and the number of remaining OTUs, , is listed.
The is a threshold for a correlation coefficient corresponding to the E-value (the P-value ) in the Student's t-distribution of the degree of freedom, , where is the number of site pairs, and is the number of OTUs.
TP and FP are the numbers of true and false positives, which are the number of contact site pairs and the number of non-contact site pairs predicted as contacts in each category, respectively.
PPV stands for a positive predictive value; i.e., .
‡The numbers of contacts and of sites, and their ratio are listed. Protein structures used to calculate contact residue pairs are listed in Table 1. Neighboring residue pairs within 5 residues () along a peptide chain are excluded in the evaluation of prediction accuracy. Also both terminal sites are excluded from counting in this table.