Adjustment problems and derived data sets

• Census Offices use various methods to reduce disclosure risk

• 1991 data in some tables suppressed by OPCS: Rees and Duke-Williams have re-estimated missing data: SMSGAPS is derived data set

• 1991 data underenumerated: Simpson and Middleton have made corrections to age-sex table: MIGPOP is derived data set

• Small cell adjustment method (SCAM) used in 2001 involving adjustment of all values of 1 and 2