English: Population pyramid of Indonesia generated from adjusted 1961 census data using Microsoft Excel 365.

Data used is not actual census data and was adjusted by economist Widjojo Nitisastro: "Census data are always subject to errors owing to inaccurate reporting of ages and to underenumeration of certain ages. For example, it is known that the age group 0–4 is often subject to serious underenumeration. Also, successive five-year age groups may be alternately overstated and understated owing to the attraction of certain ages. In order to minimize the effect of such irregularities, some simple methods of adjustment have been applied to the sex-age data of the census, while at the same time preserving the census totals for each of the sexes. Thus, the total number of the adjusted population and the ratio between the totals of the two sexes remain identical to those in the unadjusted census data. Moreoever, since it is known that the small proportion of persons in the 10–19 age group is indeed a reflection of exceptional developments in vital rates during the forties rather than the result of misstatements of ages or underenumeration, no adjustments have been applied to this group. The difference between the adjusted and unadjusted data for this age group is due to prorating applied to the data as a whole."

Source: Nitisastro, Widjojo (2006) Population Trends in Indonesia, Equinox Publishing Indonesia, pp. 202–203 ISBN: 978-979-3780-43-6.