I disagree that PEG is the "only number used to normalize"(whatever that means)in comparing companies from different sectors. Perhaps good enough for your due diligence, but not mine. The PEG is a primary measure of a company's comparison with another perhaps unrelated investment prospect, but a company's domination of its business sector should be more important to the investor than just PEG used alone.
only if the markets in which they dominate are moving in the same direction at the same rate...as an example, Dupont dominates chemicals..so would you buy that instead of EMC because it might be more dominant? Therefore I use PEG to try and normalize ( make a normal comparison) these very different companies from very different sectors..Dominating a sector that is a dog does not do much for me..