부산대학교 도서관

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.