This study assessed the quality of the age-sex data from 1991 and 2006 Nigeria population censuses using some
conventional techniques of evaluating demographic data quality. Whipple and Myers indices were used to determine the
extent of digit preference for the age-sex data presented in single years. There were very obvious preference for ages
with end-digits 0 and 5 while other end-digits were avoided in the two censuses; and this was more pronounced with the
females than males. From 1991 census to 2006 census, the Whipple index for both sexes declined from 294 to 251,
while the Myers index declined from 60.8 to 49.9; indications of deficiencies in the Nigeria censuses data. The Joint
scores computed for the five-year abridged distribution of the age-sex data yielded 54.83 and 38.52 for the 1991 and
2006 censuses, respectively. This showed that the data are poor in quality and not completely reliable as a result of
misreporting. The 29.7% decline in Joint score from 1991 census to 2006 census was an indication of a modest
improvement in quality over than fifteen years interval, even as the 2006 age-sex data are usable with adjustment.