Identifying the genetic loci contributing to variation in traits which are quantitative in nature (such as the yield from an agricultural crop or the number of abdominal bristles on a fruit fly) is a problem of great importance to biologists. The number and effects of such loci (called quantitative trait loci or QTLs) help us to understand the biochemical basis of these traits, and of their evolution in populations over time. Moreover, knowledge of these loci can aid in designing selection experiments to improve the traits.
There are a large number of different methods for identifying the QTLs segregating in an experimental cross. Little has been written critically comparing the methods, and there have been few studies comparing their performance; we make an attempt at this.