• an underestimate of the number of children below age five*
• an over-estimate of the number of teenagers aged between 10 and 20
• an underestimate of the number of men relative to the number of women*
• an underestimate of the number in the white population
• higher than expected numbers aged 80 and older, in the African population
• an underestimate of the number of foreign-born, since some identified themselves incorrectly as being South African-born
• age misstatement in the range 60-74
• an overestimate of the extent of unemployment
• an underestimate of those who were employed for only a few hours per week
• an underestimate of household income
• an overestimate the number of paternal orphans and the number of fathers missing from the household.

In addition:

Scanning problems caused some births to be recorded in the wrong province. The number of  cases is relatively small and should not lead to too much distortion for most purposes for which these data are used; however, it does produce obviously erroneous results in when one tries to estimate the extent of inter-provincial migration of those born since the previous census.

• The fertility data (numbers of children ever born, children surviving) are problematic.

For further details of these investigations see the full report of the

*
This is a common feature of censuses, particularly in developing countries.