... Why is it that detection of emission lines is more reliable than that of absorption lines? ... When you look at the iconic Figure 1 from Protassov et al (2002) , which shows how the null distribution of the Likelihood Ratio Test (LRT) and how it holds up for testing the existence of emission and absorption lines. The thin vertical lines are the nominal F-test cutoffs for a 5% false positive rate. ... Tags: absorption line , emission line , F-test , LRT , Protassov , question for statisticians . ...