On the Analysis of Optical Mapping Data - University of Wisconsin ...

35
30
0.700 − 0.005
0 50 100 150 200 250
0.750 − 0.005 0.800 − 0.005
20
10
0
−10
0.700 − 0.003 0.750 − 0.003
0.800 − 0.003
30
20
difference
10
0
30
0.700 − 0.001 0.750 − 0.001
0.800 − 0.001
−10
20
10
0
−10
0 50 100 150 200 250
mean
0 50 100 150 200 250
Figure 2.7 As we saw in Figure 2.2, it is often helpful to look at rotated Q-Q plots so that
deviations from the diagonal are emphasized. In this mean-difference plot, which effectively
rotates each panel in Figure 2.6 clockwise by 45 ◦ , systematic patterns are apparent that were
not obvious in the earlier plot. In particular, this plot gives more insight into the subtler
effect of the spurious cut rate. Recall that the distribution of fragment lengths is roughly
comparable to an exponential distribution with mean 20 Kb, so more than 99% of fragments
are shorter than 100 Kb.