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THE EFFECT OF INTRASPECIFIC SAMPLE SIZE ON TYPE I AND TYPE II ERROR RATES IN COMPARATIVE STUDIES
Article first published online: 9 MAY 2007
Volume 59, Issue 12, pages 2705–2710, December 2005
How to Cite
Harmon, L. J. and Losos, J. B. (2005), THE EFFECT OF INTRASPECIFIC SAMPLE SIZE ON TYPE I AND TYPE II ERROR RATES IN COMPARATIVE STUDIES. Evolution, 59: 2705–2710. doi: 10.1111/j.0014-3820.2005.tb00981.x
- Issue published online: 9 MAY 2007
- Article first published online: 9 MAY 2007
- Received April 22, 2005. September 29, 2005
- Independent contrasts;
- measurement error;
- phylogenetic comparative method;
- population variation;
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 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.