Dr Gatsonis has contributed extensively to statistical methods for the evaluation of diagnostic tests and biomarkers. He has published on methodology for ROC analysis for detection and prediction and on broader issues of study design in diagnostic test and imaging biomarker evaluation and validation. Dr Gatsonis has long-term involvement in the development of Bayesian statistical methods for problems in biomedical research. He developed and applied hierarchical regression models to the analysis variations in utilization, outcomes, and quality of health care, meta-analysis of diagnostic test accuracy studies, and the variability in diagnostic performance among radiologists and institutions.