The calculation of simple ages in population projections

This study describes a method of interpolation to disaggregate into single ages populations estimated or projected by five-year age groups. The method minimum roughness obviates the problem of spurious variations, which is a rather frequent problem in interpolations using multipliers. These are fluctuations that appear in the distribution by simple ages resulting from mathematical operations included in the method of interpolation and not from the demographic dynamics. Irrespective of its ability to avoid this problem, the method is convenient by its own merit, and represents an advantageous alternative to the use of multipliers in the disaggregation of age groups by single ages.