CSEW estimates are based on analysis of structured face-to-face interviews carried out using computer-assisted personal interviewing. In 2016/17, 74% of respondents completed the survey.
The CSEW is a household sample survey. Estimates are based on a representative sample of the population of England and Wales aged 16 and over. A sample, as used in the CSEW, is a small-scale representation of the population from which it is drawn.
Weighting is used to adjust the results of a survey to make them representative of the population and improve their accuracy.
For example, a survey which contains 25% women and 75% men will not accurately reflect the views of the general population, which we know has an even 50/50 split. Statisticians rebalance or ‘weight’ the survey results to more accurately represent the general population.
Survey weights are usually applied to make sure the survey sample has broadly the same gender, age, ethnic and geographic make up as the general population.
The CSEW collects information from approximately 35,000 households each year. Since those responses reflect only a fraction of the total population of England and Wales, a process is used to give different weights to different households and individuals based on their sex, age and region, in such a way that the weighted distribution of responding household and individuals in these households matches the known distribution in the population as a whole.
First, weighting is applied to the raw data to compensate for:
- unequal address selection probabilities (given, some areas are more populated than others)
- the observed variation in response rates between different types of neighbourhood
- situations in which only one dwelling unit can be selected in multiple ‘dwelling unit' households
- different probabilities of a respondent being selected based on different sized households
Second, calibration weighting is used to make adjustments for known differences in response rates between different regions and between different age groups.
The National Statistics Socio-economic Classification (NS-SEC) categorises members of the adult public in the UK according to their occupational status.
The NS-SEC categories are:
- managerial and professional occupations
- intermediate occupations (clerical, sales, service)
- routine and manual occupations
- never worked and long-term unemployed
- full-time students
- not classified
Suppression rules and disclosure control
Estimates based on fewer than 50 respondents have been suppressed as they are less reliable.
Estimates in the charts and tables are given to the nearest whole number. You can see more detailed estimates (rounded to 1 decimal place) if you download the data.Quality and methodology information
Further technical information
Since the Crime Survey for England and Wales (CSEW) is based on a sample of the population, estimates have a margin of quantifiable and non-quantifiable error associated with them.
Non-quantifiable error includes:
- when respondents have recalled crimes in the reference period that actually occurred outside that period
- crimes that did occur in the reference period that were not mentioned at all (either because respondents failed to recall a fairly trivial incident or, conversely, because they did not want to disclose an incident, such as a domestic assault)
- respondents saying they reported crimes to police when they did not (a “socially desirable” response)
- some incidents reported during the interview being miscoded (‘interviewer or coder error’)