This paper introduces the Objective Fitness Correlation, a new tool to analyze the evaluation accuracy of coevolutionary algorithms. Accurate evaluation is an essential ingredient in creating adequate coevolutionary dynamics. Based on the notion of a solution concept, a new definition for objective fitness in coevolution is provided. The correlation between the objective fitness and the subjective fitness used in a coevolutionary algorithm yields the Objective Fitness Correlation. The OFC measure is applied to three coevolutionary evaluation methods. It is found that the Objective Fitness Correlation varies substantially over time. Moreover, a high OFC is found to correspond to periods where the algorithm is able to increase the objective quality of individuals. This is evidence of the utility of OFC as a measure to evaluate and compare coevolutionary evaluation mechanisms. The Objective Fitness Correlation (OFC) provides a precise analytical tool to measure the accuracy of evaluation in coevolutionary algorithms.