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THE EFFECT OF INTRASPECIFIC SAMPLE SIZE ON TYPE I AND TYPE II ERROR RATES IN COMPARATIVE STUDIES
Author(s) -
Harmon Luke J.,
Losos Jonathan B.
Publication year - 2005
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2005.tb00981.x
Subject(s) - intraspecific competition , sample size determination , type i and type ii errors , biology , statistics , variance (accounting) , phylogenetic tree , sample (material) , statistical power , evolutionary biology , econometrics , ecology , mathematics , genetics , accounting , gene , business , chemistry , chromatography
Comparative studies have increased greatly in number in recent years due to advances in statistical and phylogenetic methodologies. For these studies, a trade‐off often exists between the number of species that can be included in any given study and the number of individuals examined per species. Here, we describe a simple simulation study examining the effect of intraspecific sample size on statistical error in comparative studies. We find that ignoring measurement error has no effect on type I error of nonphylogenetic analyses, but can lead to increased type I error under some circumstances when using independent contrasts. We suggest using ANOVA to evaluate the relative amounts of within‐ and between‐species variation when considering a phylogenetic comparative study. If withinspecies variance is particularly large and intraspecific sample sizes small, then either larger sample sizes or comparative methods that account for measurement error are necessary.