The radiologists in this study had read 6,969 mammograms on average over the preceding year. That's about 15X the certification requirement and 4X the average

The radiologists in this study had read 6,969 mammograms on average over the preceding year. That's about 15X the certification requirement and 4X the average for U.S. doctors. Reading volume is one of the main predictors of performance[1], which suggests that these doctors were probably above-average readers. It would have been nice to see more readers involved, but reader studies are a major effort. Even with the small sample size of readers, these results were statistically significant as well as clinically significant. [1] https://www.ncbi.nlm.nih.gov/pubmed/21343539 https://www.ncbi.nlm.nih.gov/pubmed/21343539