Introduction to ESDS Government surveys and

services

Vanessa HigginsESDS Government

Centre for Census and Survey Research (CCSR)

University of Manchester

My mission…

• Intro to Economic and Social Data Service (ESDS) and how we can help you

• What data is available and what it is like

• Registration and access

• Key issues to consider when analysing the data

Intro to ESDS Government and how

we can help you

ESDS Government

• ESDS began in Jan 03

• Comprises 4 specialist services– ESDS Government– ESDS Longitudinal– ESDS Qualidata– ESDS International

• ESDS Government provides access and user support for key large-scale government surveys such as Labour Force Survey, Expenditure and Food Survey etc

• Access remains via the UKDA

                     

                     

ESDS Government - some of the things we do!

• Helpdesk (govsurveys@esds.ac.uk or 0161 275 1980)

• Survey pages incl. how to get started

• Online guides – SPSS, STATA, Weighting, Employment Research, Health Research, Social Capital, Data Sources for Scotland

• User Group seminars (data users and data creators)

• Publications Database

• Derived variables - consistent over time- consistent with Census

• Teaching datasets

• Training

http://www.esds.ac.uk/government

What data is available and what it

is like?

Which surveys?

• General Household Survey/Continuous Household Survey

• Labour Force Survey/NI LFS• Expenditure and Food Survey (previously the National

Food Survey and Family Expenditure Survey) • Family Resources Survey • Time Use Survey • British Social Attitudes/Scottish Social

Attitudes/Northern Ireland Life & Times/Young People’s Social Attitudes

• ONS Omnibus Survey • Annual Population Survey• National Travel Survey • British Crime Survey/Scottish Crime Survey• Health Survey for England/Wales/Scotland• Survey of English Housing

Integrated Household Survey (Continuous Population Survey)

• Will bring together – Labour Force Survey– Annual Population Survey – General Household Survey– Expenditure and Food Survey– Omnibus Survey

• Expected to start c. 2008• Materials on our website• IHS Consultation Meeting 23rd January 2006

(pm)

Microdata

QUALITY OF DATA• Main data collectors:

– Office for National Statistics (ONS)– Central Survey Unit of the Northern Ireland

Research and Statistics Agency (NISRA) – National Centre for Social Research (NatCen)

• Very experienced in design, management and analysis of social surveys

• Permanent panels of highly trained field interviewers

• Management and Quality Checking• (Relatively) high response rates – but falling• Widespread use by secondary analysts

Registration and access

Registration• All users can access study descriptions, online

documentation, including questionnaires, free of charge without registering with ESDS

• In order to access the datasets you need to register with ESDS– Register online using your ATHENS username and

password – Simple online form, takes about 10 minutes– You need to register a usage of the data as part of this

process– Non-commercial users: free of charge – Commercial users: £500 Charge for per study and will

need to apply for ATHENs username and password – You need to agree to the End User Licence when

you register

The End User Licence• This is not public data!• We need to know who you are, how to contact

you and what you are using the data for• Agree not to attempt to identify individuals• Only use the data for your stated purpose (you can

re-register if you want to use the data for another use)

• Do not pass the data to unregistered parties (that includes deleting the data before passing on PCs!)

• Tell us if you publish using the data• Some more sensitive or detailed datasets require

more stringent licensing procedures– Special conditions: British Crime Survey– Special licences: Annual Population Survey and Labour

Force Survey at the moment

Special Licences• Agreement between ONS and ESDS • Data where the disclosure risk is deemed too high for

standard dissemination methods. E.g.:– Local authority level microdata– Month of birth

• Paper application procedure – Need to agree to stringent data stewardship conditions– Required to read the guide to good practice– Application has to be approved by ONS

• Annual Population Survey and Labour Force Survey at the moment but hope to roll out to other surveys

Registering the data for teaching

• If all students are registered ESDS users, you should register a new use of data, tick ‘teaching only’ and add the name of each student to the usage details

• If students are not registered ESDS users a paper form can be used for teaching

• Lecturer takes responsibility for the class• Students simply fill their details in on a paper

form• Return form to the UK Data Archive

Obtaining data once registered

• Choice of downloading entire files:– SPSS, Stata, tab delimited formats for most files– Comes zipped up with documentation

• Or explore the data and download subsets in Nesstar (c. 200 files in this format – including most of the Government surveys)– Allows you to explore metadata without being

registered– Can do basic exploratory anlyses (including OLS)

online without downloading files– Can define subsets to download in a wider range

of formats including SAS

Key issues when analysing the data

- Choosing the appropriate survey- Using the documentation- Using the appropriate file/dataset- Preparing the variables for analysis- Weighting- Sample size and sampling error

Choosing a dataset for research

• Is secondary analysis appropriate? – And has someone already done the analysis for you?– Check published reports.

• Is population data available?– If data is available for 100% of your population of

interest this is preferable to sample data.

• Which datasets cover your main topic?• Which other topics are you interested in?• Measurement over time• Geography• Respondents – whole household, children?• Sample size• This information will be in the documentation • To help with the decision

– ESDS Getting Started guides– ESDS topic guides

Documentation • VERY important to read the documentation before

you start the analysis• Documentation available online from UKDA/ESDS• Don’t need to be registered• Should contain

– Information about method/sampling/response– Codebooks of variables– Information about derived variables– Questionnaires

Unless you can track the variable back to the question asked, and work out who it was asked of, you don’t understand the data!

Documentation - GHS Questionnaire

Survey year : 2000/05Variable Name : ECSTILOVariable Label : ECON STAT LST WK -

ILO UNEMPLOYMENT DEFTopic : EmploymentPopulation : AdultsStandard/trailer : StandardHhld/indiv.level : IndividualRange : 1 to 10Missing values : -6, -8Priority coded : YProgram : SDate written : 12.04.96Date last amended : 30.11.98VALUE LABELS ECSTILO( -8 ) NA, ECSTA NOT KNOWN( -6 ) UNDER 16, MS( 1 ) WORKING (INCL UNPAID FW)( 2 ) GOVT SCH WTH EMP( 3 ) GOVT SCH AT COLL( 4 ) UNEMP (ILO DEF)( 5 ) OTHER UNEMPLOYED( 6 ) PERM UNABLE WORK( 7 ) RETIRED( 8 ) KEEPING HOUSE( 9 ) STUDENT( 10 ) OTHER ECON INACT

derivation :IF (SCHEDTYP EQ 3 OR AGE LT 16) = -6ELSEIF (TRNCHKA EQ 3) = 1ELSEIF (TRNCHKA EQ 1) = 2ELSEIF (TRNCHKA EQ 2) = 3ELSEIF (UNPDWKR EQ 1) = 1ELSEIF (TRNCHKA EQ 4) = 4ELSEIF (TRNCHKA EQ 5)IF (ABLESTRT EQ 1) = 4ELSEIF (ABLESTRT EQ 2) = 5ELSE = -8ELSEIF (TRNCHKA EQ 6)IF (LOOKWORK EQ -8 OR ABLSTRT EQ -8) = -8ELSEIF (LOOKWORK EQ 1 AND ABLESTRT EQ 1) = 4ELSE = 5ELSEIF (TRNCHKA EQ 7)IF (ACTIVITY EQ 2) = 6ELSEIF (WANTAJOB EQ -8 OR NABLSTRT EQ -8 OR NLOOKWRK EQ -8) = -8ELSEIF (WANTAJOB EQ -9) = 7ELSEIF (NABLSTRT EQ 1 AND NLOOKWRK EQ 1) = 4ELSEIF (ACTIVITY EQ 3) = 7ELSEIF (ACTIVITY EQ 4) = 8ELSEIF (ACTIVITY EQ 5) = 10ELSEIF (ACTIVITY EQ 1) = 9ELSEIF (TRNCHKA EQ -9) = -8

Derived variables

Using the appropriate files

• Once you have downloaded data you need to ensure you are using the file you need

• Each survey differs in format

• Formats can differ within surveys

• Some surveys/years have one file with all the data

• Some surveys have lots of different files– Separate files for topics– Separate files for unit of analysis

• Household• Individual• Carers

– What is your unit of analysis?

Preparing variables for analysis

• These datasets contain hundreds of variables– Straightforward and complex questionnaire

variables– Straightforward and complex derived variables– Often many variables on the same topic– Are you using the optimum variable available?

• Categories• Population base

– Do you need to derive your own variable from those available?

– How are missing values dealt with?

Unless you can track the variable back to the question asked, and work out who it was asked of, you don’t understand the data!

Weighting• Weighting is becoming increasingly important/common• Weighting corrects for known bias in datasets• Bias arises because of:

– Sample design e.g. when one individual per household is selected for a sample or one group of the population e.g. children, are over-sampled to boost numbers

– non-response i.e. unequally distributed non-response• Third form of weighting often referred to as grossing which weights to

produce population estimates• Different packages handle weighting differently

http://www.esds.ac.uk/government/resources/statguides.asp

– are weights available?– how does the documentation suggest you use

the weights?– what will your analysis package do with

weights?

Sample size and sampling error

• Sample data is subject to sampling error

• The larger the sample the greater the accuracy with which the sample represents the population

• If the sample is small it may, by chance, be different from the population

• Govt surveys often publish a range of sampling errors for their main point estimates but you will probably need to calculate some yourself

Good practice:Some pointers

• Irresponsible use can threaten future access• Keep data secure • You won’t understand the data unless you consult the

documentation!• Consider the impact of the sample design

– Sample data has sample error; small cell counts are likely to be unreliable

– Will the sampling design affect the standard errors?– Does weighting need to be applied to avoid bias

• Getting started guides, stats guides and topic guides are available on the ESDS site if you don’t know where to start

• Contact helpdesk if you have any problems or find errors in the data

• User groups and news lists can help keep you informed • Published results from surveys and published articles that

have used the surveys• Survey Link Scheme – can attend an interview

yourself http://qb.soc.surrey.ac.uk/sls.htm

Using the data in teaching• Methods courses

– Using the data in a hands on manner– Using substantive exemplars to demonstrate a

methodological point– Using the surveys as methodological exemplars

• Substantive courses– Making your point using data– Integrating methods into substantive courses

• Teaching datasets– General Household Survey– Labour Force Survey– British Crime Survey– Health Survey for England

Some other useful resources

• Question Bank– Linked to from ESDS– Contains searchable questionnaires for major

surveys– Contains articles about major topics/concepts– Runs the survey link scheme– http://qb.soc.surrey.ac.uk

• PEAS (Practical Exemplars on the Analysis of Surveys)– Contains learning materials on the impact of

survey design on analysis (e.g. weighting and complex sample designs)

– Uses the government surveys as exemplars– http://www.napier.ac.uk/depts/fhls/peas

• ONS website contains published reports, methodology etc.– http://www.statistics.gov.uk

The important last slide…

Helpdesk: govsurveys@esds.ac.uk

(0161)275 1980

Website:http://www.esds.ac.uk/government

JISCmail: esds-govsurveys@jiscmail.ac.uk