Optimizing Strategies to Maximize Patient Recruitment Yield

Inclusion Criteria for primary studies that are recruiting participants: * All studies using the MyChart recruitment service are eligible, including both clinical trials and observational studies. Exclusion Criterion for primary studies that are recruiting participants: * Not using MyChart for recruitment. * At least 500 messages sent, 125 for each arm Inclusion Criteria for patients: * All patients receiving messages via MyChart will be included * Potential eligibility for a study using MyChart requirement based on the planned query/criteria for that study. Exclusion Criteria for patients: * Minor * Excluded from primary study that is recruiting participants.