  The presence of uncommon taxa in high-throughput sequenced ecological samples
pose challenges to the microbial ecologist, bioinformatician and statistician.
It is rarely certain whether these taxa are truly present in the sample or the
result of sequencing errors. Unfortunately, alpha-diversity quantification
relies on accurate frequency counts, which can rarely be guaranteed. We present
a species richness estimation tool which predicts both the number of unobserved
taxa and the number of true singletons based on the non-singleton frequency
counts. This method can be treated as either inferential (for formally
estimating richness) or exploratory (for assessing robustness of the richness
estimate to the singleton count). If the estimate, called breakaway_nof1, is
comparable to other richness estimators, this provides evidence that the
richness estimate is robust to the level of quality control (eg.
chimera-checking) employed in pre-processing. The function breakaway_nof1 is
freely available from CRAN via the R package breakaway.
