Mark, inflation pass through is a management decision which may be dependent upon company competitive position, customer/product price elasticity, industry maturity, substitute product availability, compensation policy, stage of business cycle, macro economic growth conditions among others. Perhaps your sample data is reflecting the end result of these decisions at the micro level. If ROE is maintained at nominal prices, there is a case for hedge against inflation. At the investment portfolio level, you will have to observe the inflation differential in the return of investment to arrive at a conclusion regarding the efficacy of the investment and the asset class as an inflation hedge.