Registration is open now for a webinar on December 14 from noon to 1 p.m. ET that will describe the major reasons why nearly all patient registries have some missing data, which can affect the accuracy of conclusions by reducing power and introducing bias. Data are often missing or incomplete in observational studies, such as losses to follow-up and censoring. Registry design and operational strategies that can help minimize missing data will be discussed. Presenters will also describe methods for analyzing datasets with missing data, ways to document the extent of missing data, and the importance of transparency to allow audiences to appropriately interpret and apply registry findings. This webinar is part of a series hosted by AHRQ’s Registry of Patient Registries project, a central, searchable database of patient registries that is integrated with ClinicalTrials.gov.