1. Kaiser Permanente Washington Health Research Institute, Seattle, Washington, USA
2. Privacy Analytics Inc, Ottawa, Ontario, Canada
3. Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
4. Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
5. Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee, USA
6. The MITRE Corp, Bedford, Massachusetts, USA