The need for nationally representative longitudinal data for addressing key questions about family change

The United States is undergoing rapid social change. The nation faces declines in stable family formation, related to growing income inequalities and stalled improvements in population health. This essay considers key questions about families in the United States and whether a new nationally representative panel study is necessary to answer these questions. It argues that current data systems are not well equipped to evaluate the potential sources of these changes over historical time. Most of our longitudinal data systems are designed to follow a single cohort as it ages. This provides an incomplete picture, one that ignores period context, because cohort studies confound period changes with aging. Comparisons across cohort studies can be helpful, but leave a wide gap in our knowledge. A new nationally representative panel study would fill that gap.