Spearman rank (ρ) and log-log transformed Pearson (r) correlation coefficients of error-free sequences with their respective theoretical frequencies.

The pools of error-free sequences for V6P and V6T (33,804 and 39,978 reads respectively) were resampled 10,000 times with replacement to match the numbers of V3V4P and V3V4T error-free sequences (5,424 and 6,607 reads respectively). The correlation coefficients for each bootstrap were calculated and presented as means and 95% confidence intervals. The bootstrapping p values (testing the V6x correlation coefficients as higher than the V3V4x equivalents) were 0.814 (ρ) and 0.152 (r) for resampled V6P vs. V3V4P and r) for resampled V6T vs. V3V4T.