¹Department of Botany and Plant Sciences, University of California, Riverside, CA, USA

Correspondence: Professor Shizhong Xu, Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA. E-mail: shizhong.xu@ucr.edu

Received 29 November 2007; Revised 18 February 2008; Accepted 17 March 2008; Published online 30 April 2008.

Abstract

We developed a simple method for calculating the statistical power for detecting a QTL located in an interval flanked by two markers. The statistical method for QTL detection is assumed to be the Haley and Knott's simple regression method of interval mapping. This method allows us to answer one of the fundamental questions in designing a QTL mapping experiment: What is the minimum marker density required to detect a QTL explaining a certain heritable proportion of the phenotypic variance (denoted by h²) with a power under a Type I error in an F₂ or other mating designs with a sample size n? Computing the statistical power only requires the ability to evaluate a non-central F-distribution function and the inverse function of this distribution.