The effect of intraspecific sample size on type I and type II error rates in comparative studies

Luke J. Harmon, Jonathan B. Losos

Research output: Contribution to journalArticlepeer-review

95 Scopus citations

Abstract

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 within-species variance is particularly large and intraspecific sample sizes small, then either larger sample sizes or comparative methods that account for measurement error are necessary.

Original languageEnglish
Pages (from-to)2705-2710
Number of pages6
JournalEvolution
Volume59
Issue number12
DOIs
StatePublished - Dec 2005

Keywords

  • Independent contrasts
  • Measurement error
  • Phylogenetic comparative method
  • Population variation
  • Statistics

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