In the spotlight - changes to the General Household Survey

Article dated: 27 May 2008

The Office for National Statistics (ONS) General Household Survey (GHS) began in 1971 and has provided key statistics for Great Britain on household characteristics, fertility, smoking and drinking, healthy life expectancy, income and many other topics over more than 30 years. However, the GHS has recently changed to form the General Lifestyle module (GLF) on the ONS Continuous Population Survey. It also provides the UK data for the European Union Statistics on Income and Living Conditions (EU-SILC), collected for 27 EU member states and now available in CD-ROM for research analysis.

Whilst the GHS was an annual cross-sectional survey, a consequence of EU-SILC meant that, in 2005, it changed its sample design to a 4-year sample rotation, illustrated below, which provides both cross-sectional and longitudinal information. The annual sample size is about 10,000 achieved households. From 2008 onwards, once the survey is in 'steady state', a quarter of the sample will be replaced each year (giving an overlap of 75 per cent between successive years).

From Murray and Matthews presentation to GHS User Meeting, March 2008

Initial members of the survey household are followed over the four-year period – even if they leave the original household. If they join/form a new household all household members are interviewed, although 'new' household members are not followed if they are no longer living with an original member. A complete longitudinal survey will be available by the end of the 2008 interviewing.

The ONS survey team are doing a great deal of work to maintain the longitudinal response rates using the Keeping in Touch Exercise (KITE). The Telephone Unit(TU) KITE establishes if an individual respondent has:

• stayed at their existing household
• moved to a different address within Great Britain
• moved outside Great Britain
• moved to an institution
• has died

The questionnaire has a Core section, with household and individual questions, followed by a GLF section. There will be some topic overlap between them (e.g. health questions on both). The 2008 trailer is on financial exclusion and over-indebtedness.

A European dimension

The EU-SILC version of the GLF is a different, discrete dataset which contains variables specifically derived to meet EU requirements - these variables are used, among other things, to derive Laeken indicators, which are:

• risk of poverty thresholds
• at-risk-of-poverty rate (by age, gender, activity status, household type, tenure status, work intensity)
• dispersion around the poverty threshold
• risk of poverty before and after social transfers

Income poverty still affects 16 per cent of the EU population – i.e. they live in a household where equivalised income is below the threshold of 60 per cent of the national equivalised median income.

Methodological changes

The GLF has recently updated other aspects of its methodology. One important area is in measuring alcohol consumption. This has introduced new conversion factors when converting volumes of alcohol to units. These changes recognise:

• increases in the size of wine glasses served on licensed premises
• increased alcoholic strength of wine
• better estimates of alcoholic strengths of beers, lagers and ciders

The net result of these changes is that average weekly alcohol consumption has increased by about one third: from 10.2 units to 13.5. It is important to note that this increase does not in itself represent a real increase in alcohol consumption, rather a more precise way of converting what people say they drink into units of alcohol.

The GLF is also running a project to test a sexual identity question to reflect the needs of the Equality and Human Rights Commission which covers disability, age, gender, religion, sexual orientation, and race.