Data are essential for scientific research and policy planning. However, there needs to be attention to data quality and the estimates and models based on those data. In addition, data need to be freely available for researchers to test new ideas and validate the work of others through replication, while respondents who provide data need to be protected. Three issues concerning data are addressed: 1) Availability and accuracy of data for new research and re-analysis while protecting human subjects, 2) Problems with the estimation of indicators based on flawed or non-generalizable data, and 3) The use of data to develop models for projecting the future, the assumptions on which those models are based, and assessment of the accuracy of past projections. In each of these areas, increased attention as to how data are used, interpreted, and made available to the scholarly and policy community is necessary.