The dangers of drawing cohort profiles from period data: a research note

Alyson A. van Raalte, Ugofilippo Basellini, Carlo Giovanni Camarda, Marília R. Nepomuceno, Mikko Myrskylä

Research output: Working paperPreprint


Drawing cohort profiles and cohort forecasts from grids of age-period data is common practice in demography. In this research note, we: (1) estimate the bias in the cohort TFR and life expectancies calculated from such data, and (2) demonstrate that cohort Lee-Carter forecasts drawn from an age-period grid have implausible prediction intervals, especially when drawn from the upper and lower bounds of the time series parameter. These biases are surprisingly large, even when the cohort profiles are created from single-age, single-year period data. The danger is that we overinterpret deviations from expected trends, that in actual fact were induced by our own data manipulation.
Original languageEnglish
Place of PublicationRostock
Number of pages21
Publication statusPublished - 3 Mar 2022
MoE publication typeNot Eligible

Fields of Science

  • 5200 Other social sciences

Cite this