I have collected data on a chromatography Response Surface DOE with the goal of maximizing resolution of 4 peak pairs throughout a chromatogram. For one of these peak pairs, the resolution is so poor for some conditions that the resolution cannot be calculated. If I enter 0 for those peaks, then I'm worried the DOE analysis will artifactually skew the values of the data towards 0. If I don't enter any value, then the analysis won't include those data points to determine those factor level combinations are outside my design space. What is the best way to include information about unresolved peaks in the data tables?