Heuristics can promote a priori interesting functions, or eliminate obviously noninteresting ones.
To eliminate obviously spurious and paralogous sequences, non-bootstrapped phylogenetic trees were constructed to determine to which, if any, carotenoid biosynthetic enzyme family the recovered sequences belonged.
These cutoff levels, while eliminating obviously aberrant comparisons, also resulted in rejection (due to ds values >1.5) of most comparisons of cyanobacterial sequences, many of which are obviously only minimally divergent (Figures 2, 5 and 6).
The research team triaged items to eliminate obviously ambiguous or purely repetitive questions.
Using these criteria, sequences encoding the genes and sequences derived from intergenic regions resulting in no match to the nr protein database were identified, using manual curation to eliminate obviously spurious results (e.g., those resulting from low-complexity alignments).
This has proven to be an efficient solution, eliminating obviously benign findings and significantly reducing the number of false positives, on average by up to two per patient, both for blastic and lytic metastases.
The approach used by this program relies on a systematic analysis of all published 16S rRNA gene sequences for all streptococci (and closely related organisms), using sequence profiles to eliminate obviously incomplete or erroneous submissions, which could induce wrong alignments.
Look at the questions you're not sure of and try to eliminate obviously wrong answers, trying to fill it in with something that'll be at least in the ballpark.
Statistically, you'll stand a better chance of getting a good score on a Scantron test if you just read the answers, eliminate obviously-wrong answers, and make a halfway decent guess.
