Smith S K, Sincich T
College of Business Administration, University of Florida 32611.
Demography. 1988 Aug;25(3):461-74.
A number of studies in recent years have investigated empirical approaches to the production of confidence intervals for population projections. The critical assumption underlying these approaches is that the distribution of forecast errors remains stable over time. In this article, we evaluate this assumption by making population projections for states for a number of time periods during the 20th century, comparing these projections with census enumerations to determine forecast errors, and analyzing the stability of the resulting error distributions over time. These data are then used to construct and test empirical confidence limits. We find that in this sample the distribution of absolute percentage errors remained relatively stable over time and data on past forecast errors provided very useful predictions of future forecast errors.
近年来，许多研究探讨了用于人口预测的置信区间生成的实证方法。这些方法所基于的关键假设是，预测误差的分布随时间保持稳定。在本文中，我们通过对20世纪多个时间段的各州进行人口预测、将这些预测与人口普查数据进行比较以确定预测误差，并分析所得误差分布随时间的稳定性，来评估这一假设。然后，这些数据被用于构建和检验实证置信区间。我们发现，在这个样本中，绝对百分比误差的分布随时间保持相对稳定，并且过去预测误差的数据对未来预测误差提供了非常有用的预测。
