Objectives We analyzed test volume data to identify low-value test utilization. We subsequently tracked the efficacy of interventions to improve test utilization by decreasing low-value testing. Methods Test volume data for analytes included in the Choosing Wisely guidelines were analyzed to identify population outliers. Outliers were defined by test volume ratios of either analyte to sodium or paired analytes to correct for variation in patient volumes at each site. Interventions to improve test utilization were targeted to outlier sites. Relative efficacy in reducing low-value testing was tracked at those sites. Results After appropriate data cleaning, test volume ratios for 17 analytes paired with sodium and 8 pairs of analytes were acquired from 108 national sites. A site with abnormally high Clostridium difficile/sodium ratio was selected for intervention, leading to a 71% decrease in C difficile tests. Two different interventions to decrease creatine kinase MB isoform (CKMB) testing were performed at two unique sites with abnormally high CKMB/troponin ratios. These interventions decreased CKMB by 11% and 98% at the different sites, showing the efficacy of the different kinds of interventions. Conclusions Test volume ratio analysis and benchmarking enable identification of low-value test utilization.