What are individual-level microdata and aggregate-level area census data?

What are microdata?

• Microdata are data about the socio-demographic characteristics of individual people and/or their households. Microdata constitute the data type closest in format to the original master database of census records

What are area data?

• Census Area Statistics (CAS) consist of counts for areas organised in tables. CAS are the sum of all the individual or household microdata within an area. Area data are therefore also referred to as "aggregate" data
• The figure below contains a simple example of a table with counts of people in four areas according to their age
  

• The area data constitute a fixed set of tables, which are said to be safe from disclosure risk
• Three kinds of area tables were produced from the 1991 UK Census:
  • National Topic Statistics
  • Local Base Statistics (LBS)
  • Small Area Statistics (SAS)