Hence, a threshold of about 3.56 should be used, instead of the threshold 1.96, to ensure and overall significance level of 5% in a genome scan for a backcross design with and inter-marker spacing of 10 cM.

Remark 5.2. The LOD score is a different scale of measurement often used, particularly in human genetics, to define test statistics and significance thresholds. If we denote the thresholds given above by z, the LOD threshold is given by LOD = z2/4.6. For example, the LOD threshold corresponding to z = 3.57 is LOD = 2.77. Conversely, in human genetics the LOD threshold of 3 is frequently recommended. This corresponds to a z threshold of [3 x 4.6]1/2 « 3.71. In this book, we will usually give significance thresholds as a value of z or z2. These can easily be converted to LOD thresholds.

Fig. 5.2. The distribution of \Zt\ and of maxt \Zt\

Fig. 5.2. The distribution of \Zt\ and of maxt \Zt\

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