Practice question

Human genetics requires stringent criterion because 23 chromosome pairs create many opportunities for chance cosegregation. Statistical tradition established LOD 3 as significant and LOD -2 as exclusion after Newton Morton analysis of prior odds. At LOD 3 likelihood favoring linkage exceeds 1000:1, compensating prior odds of unlinked loci about 1:50 and providing genome-wide Type I error control near 0.05. Below 3 evidence considered suggestive but inconclusive, prompting collection additional families. For complex traits newer threshold 3.3 from Lander and Kruglyak accounts higher multiple testing burden in genome scans.