ACT currently appears to be about as effective as standard CBT, with some meta-analyses showing small differences in favor of ACT and others not. For example, a meta-analysis published by Francisco Ruiz in 2012 looked at 16 studies comparing ACT to standard CBT. ACT failed to separate from CBT on effect sizes for anxiety, however modest benefits were found with ACT compare to CBT for anxiety and quality of life. The author did find separation between ACT and CBT on the "primary outcome" – a heterogeneous class of 14 separate outcome measures that were aggregated into the effect size analysis. This analysis however is limited by the highly heterogeneous nature of the outcome variables used in the analysis, which has the tendency to increase the number needed to treat (NNT) to replicate the effect size reported. More limited measures, such as depression, anxiety and quality of life decrease the NNT, making the analysis more clinically relevant, and on these measures ACT did not outperform CBT.