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Biomedical subjects

F R McMorris

Publications and source records attributed to F R McMorris.

7 recordsLinked to original sources
PubMed1992

Threshold consensus methods for molecular sequences.

We introduce a parameterized threshold consensus method (th chi) for molecular sequences which is based on a majority-rule voting principle. In contrast to other frequency-based methods, the th chi method uses a single criterion to return ambiguity codes of different lengths. We derive basic features of the method and establish that it returns at most two ambiguity codes at any position of the consensus sequence. We bound from below the size of the frequency gap that exists when the th chi method returns an ambiguity code. Using such properties, we compare the th chi method to other consensus methods for molecular sequences which are defined in terms of threshold or gap criteria.

Base Sequence↗
PubMed1992

Critical comparison of consensus methods for molecular sequences.

Consensus methods are recognized as valuable tools for data analysis, especially when some sort of data aggregation is desired. Although consensus methods for sequences play a vital role in molecular biology, researchers pay little heed to the features and limitations of such methods, and so there are risks that criteria for constructing consensus sequences will be misused or misunderstood. To understand better the issues involved, we conducted a critical comparison of nine consensus methods for sequences, of which eight were used in papers appearing in this journal. We report the results of that comparison, and we make recommendations which we hope will assist researchers when they must select particular consensus methods for particular applications.

Algorithms↗
PubMed1992

Interpreting consensus sequences based on plurality rule.

Our goal is to help researchers interpret the results of a function, based on the concept of plurality rule, that calculates a consensus of a profile of molecular bases. By expressing the plurality rule function as a composition of simpler functions, we obtain both an algorithm to calculate the consensus result and an upper bound on the number of nonequivalent results. Consequently, when used to analyze molecular sequences such as DNA or RNA, the plurality rule function yields at most 48 nonequivalent consensus results. For problems of reasonable size, we describe an algorithm to calculate the probability that each consensus result would occur if the bases were equally likely to appear at every position of the plurality rule function's input profile.

Algorithms↗
PubMed1991

Consensus weak hierarchies.

An axiomatic characterization is presented for consensus functions defined on weak hierarchies. These functions are generalizations of the majority rule consensus.

Classification↗
PubMed1977

When are two qualitative taxonomic characters compatible?

A proof is given of a procedure that has previously appeared claiming to determine when two amino acid positions on a protein could both possibly be divergent taxonomic characters. An algorithm for executing this procedure is described.

Amino Acid Sequence↗