Error in Displayed Signal Amplitude due to Noise

Let's see what happened to our dynamic range as a result of our concern
with measurement error. As Figure 6-6 shows, second-order-distortion
dynamic range changes from 72.5 to 61 dB, a change of 11.5 dB. This is one
half the total offsets for the two curves (18 dB for distortion; 5 dB for noise) .
Third-order distortion changes from 81.7 dB to about 72.7 dB for a change
of about 9 dB. In this case, the change is one third of the 18 dB offset for the
distortion curve plus two thirds of the 5 dB offset for the noise curve.

Figure 6-7. Error in displayed signal amplitude due to noise