Recent decades have seen a series of attempts to further develop measures of implicit bias. Some observers have suggested drawing on lessons learned in the literature on optimal measurement of explicit bias to enhance implicit bias measures. Suggestions have also been made about how to improve meta-analyses of studies quantifying the strength of the link between implicit attitudes and behavior. For example, outdated statistical methods used in many meta-analyses of implicit bias may have led to incorrect inferences about the average effect sizes and can be avoided using newer techniques. Further improvement has been suggested to more effectively take into account omitted variables that may create spurious associations of implicit attitudes and behavior.