A comparison of different methods for decomposition of changes in expectation of life at birth and differentials in life expectancy at birth

Several methods were proposed to decompose the difference between two life expectancies at birth into the contribution by different age groups. In this study an attempt has been made to compare different methods with that of Chandra Sekar (1949) method. The methodologies suggested by Arriaga, Lopez and Ruzicka and Pollard have been extended. It is shown that all the three methods and also Chandra Sekar method in their modified (symmetrical) form will be seen to produce the same result as that of United Nations, Pollard, Andreev and Pressat. Finally it is suggested to use symmetric formulae of the above methods because the percent contribution of total of the interaction terms to the difference in the life expectancy at birth is observed to be very negligible.