Varying spectral conditions for XPS doublets were simulated according to a factorial design with three factors as shown in the figure below. (Note that binding energy is along the horizontal axis. Binding energy decreases from left to right.) Separation between component peaks in the doublet was modeled as Factor 1 with three levels:

1. no shoulder detectable (a-c)
2. shoulder detectable (d-f)
3. valley detectable (g-i)

The relative intensities of component peaks were modeled as Factor 2 with three levels:

1. low-intensity peak on the high binding-energy side (BE) side and high-intensity peak on the low-BE side (a,d,g)
2. both peaks approximately equal (b,e,h)
3. high-intensity peak on the high-BE side and low-intensity peak on the low-BE side (c,f,i)

Fractional Poisson noise in the spectra, defined as the standard deviation (N)^1/2 where N=electron count, was modeled as Factor 3 with two levels. For the lower noise level, spectral intensity was adjusted so that Poisson noise at the peak maximum was 3% of the maximum intensity. For the higher noise level, spectra intensity was adjusted so that the Poisson noise at the peak maximum was 6% of the maximum intensity.