(1) The synthetic microdata supplied cover only the resident private household 
population as recorded in the 1991 Census

(2) Synthetic microdata are not available for enumerations districts that had counts 
suppressed by the Census Office for confidentiality reasons; as with published census outputs, suppressed individuals are included in neighbouring unsuppressed enumeration 
districts

(3) Synthetic microdata are not available for ‘special’ (institutional) EDs, although 
the Pop91 program suite can be used unchanged to produce such estimates if required

(4) Small-area census data contain minor inconsistencies between tables due to 
pre-realease confidentiality protection measures. As a result, when aggregated the 
synthetic microdata will display unavoidable minor deviations from published small-area 
counts

(5) In the synthetic microdata estimation process, published 10% SAS counts were 
replaced with modelled 100% counts wherever ward-level LBS data availability permitted; the 
resulting synthetic microdata aggregate to the modelled 100% counts rather than the 
published 10% counts

(6) No allowance has been made for potential under-enumeration

(7) Although microdata comprising any of the variables in the SAR may be extracted, only 
interactions between the 15 variables used in the data estimation process (see list of constraints) should be regarded as statistically reliable