Portfolio-based assessments in medical education: are they valid and reliable for summative purposes?

@article{Roberts2002PortfoliobasedAI,
  title={Portfolio-based assessments in medical education: are they valid and reliable for summative purposes?},
  author={Christopher Roberts and David I Newble and Alan J. O'Rourke},
  journal={Medical education},
  year={2002},
  volume={36 10},
  pages={899-900}
}