Smith Stanley K, Tayman Jeff
Bureau of Economic and Business Research, 221 Matherly Hall, University of Florida, Gainesville, FL 32611-7145, USA.
Demography. 2003 Nov;40(4):741-57. doi: 10.1353/dem.2003.0041.
A number of studies have evaluated the accuracy of projections of the size of the total population, but few have considered the accuracy of projections by age group. For many purposes, however, the relevant variable is the population of a particular age group, rather than the population as a whole. We investigated the precision and bias of a variety of age-group projections at the national and state levels in the United States and for counties in Florida. We also compared the accuracy of state and county projections that were derived from full-blown applications of the cohort-component method with the accuracy of projections that were derived from a simpler, less data-intensive version of the method. We found that age-group error patterns are different for national projections than for subnational projections; that errors are substantially larger for some age groups than for others; that differences in errors among age groups decline as the projection horizon becomes longer; and that differences in methodological complexity have no consistent impact on the precision and bias of age-group projections.
许多研究评估了总人口规模预测的准确性，但很少有研究考虑按年龄组进行预测的准确性。然而，对于许多目的而言，相关变量是特定年龄组的人口，而非总人口。我们在美国国家和州层面以及佛罗里达州各县调查了各种年龄组预测的精度和偏差。我们还比较了源自队列成分法全面应用的州和县预测的准确性与源自该方法更简单、数据密集度更低版本的预测的准确性。我们发现，国家层面的年龄组误差模式与次国家层面的不同；某些年龄组的误差比其他年龄组大得多；随着预测期变长，年龄组之间的误差差异会减小；并且方法复杂性的差异对年龄组预测的精度和偏差没有一致的影响。
