Interaction terms based on background-averaged epistasis () for an empirical multiallelic genotype-phenotype landscape consisting of all combinations of two mutations each at positions 6 and 66 in the tRNA-Arg(CCU) [6], i.e. n = 2 and s = 3.

The first two columns indicate nucleic acid sequences and their base 3 representations. Here the ‘GC’ reference (wild-type) genotype corresponds to that of S. cerevisiae, denoted by (0, 0). The second two columns show the measured phenotypic effects and corresponding background-averaged epistatic coefficients together with their empirical errors and their propagated errors. See Results for a regression analysis of the entire dataset and Proposition 8 in S1 Text for a derivation of the error propagation.