The research findings we have reviewed in this chapter should be viewed with cautious optimism. The reason for caution is that the methods used in this research have several limitations. First, most studies used cross-sectional designs that are of limited value in establishing cause and effect. Second, HRM practices were often assessed by using surveys completed by employees themselves; concerns over accuracy aside, obtaining measures of both practices and commitment from the same source can lead to inflation of the observed correlations (e.g., because of common errors in ratings ). Third, as we noted earlier, when examined in isolation, a particular HRM practice might be found to relate to commitment because of its association with other (unmeasured) HRM practices or business strategies that are the true causes of commitment.