Evidence map›Paper›PMID 28122501›Full record

ArticleBMC bioinformatics2017

Exact p-values for pairwise comparison of Friedman rank sums, with application to comparing classifiers.

Rob Eisinga, Tom Heskes, Ben Pelzer, Manfred Te Grotenhuis

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Article in BMC bioinformatics, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers.

0numbers the graph read from it
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35citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

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3 · Its place in the literature

Who cites it

35 citing papers in PubMed.

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4 · The record

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PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

4 authors.

Rob EisingaDepartment of Social Science Research Methods, Radboud University Nijmegen, PO Box 9104, , 6500 HE, Nijmegen, The Netherlands. r.eisinga@maw.ru.nl.ORCID http://orcid.org/0000-0002-8349-5226
Tom HeskesInstitute for Computing and Information Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands.
Ben PelzerDepartment of Social Science Research Methods, Radboud University Nijmegen, PO Box 9104, , 6500 HE, Nijmegen, The Netherlands.
Manfred Te GrotenhuisDepartment of Social Science Research Methods, Radboud University Nijmegen, PO Box 9104, , 6500 HE, Nijmegen, The Netherlands.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThe Friedman rank sum test is a widely-used nonparametric method in computational biology. In addition to examining the overall null hypothesis of no significant difference among any of the rank sums, it is typically of interest to conduct pairwise comparison tests. Current approaches to such tests rely on large-sample approximations, due to the numerical complexity of computing the exact distribution. These approximate methods lead to inaccurate estimates in the tail of the distribution, which is most relevant for p-value calculation.

resultsWe propose an efficient, combinatorial exact approach for calculating the probability mass distribution of the rank sum difference statistic for pairwise comparison of Friedman rank sums, and compare exact results with recommended asymptotic approximations. Whereas the chi-squared approximation performs inferiorly to exact computation overall, others, particularly the normal, perform well, except for the extreme tail. Hence exact calculation offers an improvement when small p-values occur following multiple testing correction. Exact inference also enhances the identification of significant differences whenever the observed values are close to the approximate critical value. We illustrate the proposed method in the context of biological machine learning, were Friedman rank sum difference tests are commonly used for the comparison of classifiers over multiple datasets.

conclusionsWe provide a computationally fast method to determine the exact p-value of the absolute rank sum difference of a pair of Friedman rank sums, making asymptotic tests obsolete. Calculation of exact p-values is easy to implement in statistical software and the implementation in R is provided in one of the Additional files and is also available at http://www.ru.nl/publish/pages/726696/friedmanrsd.zip .

Indexed as

User-Computer InterfaceComputational BiologyHumansInternetStatistics, NonparametricClassifier comparisonExact p-valueFriedman testMachine learningMultiple comparisonNonparametric statisticsRank sum difference

Identifiers

PMID28122501
PMCPMC5267387

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LicenceCC BY
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.