Occurrences of the compensation effect in published studies on the initial rate of heat exchanger fouling are discussed. When fouling-rate experiments are performed on a series of related fluids, it is shown that random errors in the measurements can create an apparent compensation effect. This explains some reported occurrences in the literature. Other reported instances of the compensation effect show a systematic variation in apparent activation energy with fluid flow rate. It is shown that these may be the result of analyzing the temperature dependence of the overall rate of reaction. The conditions under which the compensation effect is expected when flow rate is varied are explored using synthetic data generated by a model for chemical reaction fouling.