Existing population projections in Sri Lanka: Comparative analysis of the accuracy

Abstract

The aim of the study is to evaluate the accuracy of past population projections with the comparison of observed figures in 2001 and 2012 population censuses in Sri Lanka. It has also compared the age-sex structures of the projections with the observed data. Out of the six population projections, four had been produced by three local forecasters: Soma De Silva, W. Indralal De Silva, A. T. P. L. Abeykoon and the other two by United Nations and, all of these projections had been examined. Standard variation of four projections produced before year 2000 show a percentage error ranging from 1.16 to 3.05 with 2001 observed figures and 3.33 to 5.21 with 2012 observed figures. Other two projections produced after year 2000 have a percentage error 1.59 and -3.09, respectively, when compared with 2012 observed figures. Accuracy of observed vs. projected population, projection errors and their measurement as well as age-sex structures of two projections against 2012 observed population have been examined. The examination of accuracy of the past projection results would lead to a generation of more reliable projections in future.