Despite the multiplicity of their concerns, the principal investigators of these studies shared an assumption that there was no substitute for data collected continuously on the same people over several decades. In recent years, life-course research has flourished, as investigators have assembled longitudinal data sources and devised new methodological techniques to mine these rich achievements from the field of human development. At the Murray Research Center conference, three generations of longitudinal researchers presented important findings from life-course studies that challenge common assumptions about today's social problems and that have significant public policy implications. Greg Duncan and his colleagues showed that only a little over half of the individuals living in poverty in one year are found to be poor in the next, and considerably less than one-half of those who experience poverty remain persistently poor over many years. Similarly, many families receive income from welfare sources at least occasionally, but relatively few do so year after year.
Many delinquent youth do leave the path of crime.
Teenage mothers are not immobile. In The Baltimore Study, a long-term study of teen parents, Frank Furstenberg and his colleagues showed what happens as teen mothers become mature women and even grandparents. Only a minority had gone on to have large families that kept them on public assistance. In fact, most had returned to school at some point to advance their education and improve their labor-market prospects. Differences between educational attainments of children from wealthier neighborhoods have more to do with what happens when school is out of session than what happens in school.