Design of the 2007 Test and sample size

The 2007 Census Test was conducted in five local authority areas selected to reflect a range of field conditions, covering around 100,000 households in total. The five local authorities represented a range of area types according to the Office for National Statistics (ONS) classification:

  • Liverpool (representing Services and Cities)

  • Camden (London Centre)

  • Bath and North East Somerset (Prospering UK)

  • Carmarthenshire (Coastal and Countryside)

  • Stoke-on-Trent (Mining and Manufacturing)

One of the key requirements of the Test was to identify which fieldwork factors positively influenced response and whether these varied within different 'hard-to-count' population groups. The selected local authorities had been chosen to provide a varied cross-section of the population and types of housing that would be covered in a full census, although there was no formal attempt to generalise statistical conclusions from the test areas to the population as a whole.

The sample of households was divided into five equal categories, outlined in the Enumeration Targeting Categorisation (ETC). This is illustrated in maps of the five local authority areas. The ETC assigns a category to each census Enumeration District (ED). Each category corresponds to a difficulty level of 1 to 5, where 5 represents those areas that ONS anticipates to be the hardest.

The ETC was developed using factors found to be most associated with household census non-response (young adults, ethnicity, low income, renting from private a landlord, some other types of renting and living in non-standard housing).

Within each stratum:

  • half the population will have received a questionnaire by post and half by hand

  • half the population will have received a questionnaire including an income question, and half without

 

The basic sample design is as shown in the following table:

ETC Postout Hand delivery
Strata Income No Income Income No Income Total
1 (very easy) 5,000 5,000 5,000  5,000  20,000 
2 5,000 5,000  5,000  5,000  20,000 
- - -  -  -  - 
5 (very difficult) 5,000 5,000  5,000  5,000  20,000 
Total 25,000 25,000 25,000  25,000  100,000

 

The numbers of EDs and selected households within each local authority are:

Local authority EDs Household
Liverpool 216 40,115
Camden 168 24,880
Stoke on Trent 73 15,688
Bath and NE Somerset 51 9,835
Carmanthenshire 56 9,520
Total 564 100,038

 

Local authority area maps

Showing Enumeration Targeting Categorisation:

Enumeration District maps

Showing location of EDs within local authority areas and ETC difficulty levels:

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