UK Data Archive Study Number 4317. Quarterly Labour Force Survey, September - November, 2000 : Local Area Data. Labour Force Survey User Guide – Volume 1: Background & Methodology BACKGROUND & METHODOLOGY 2003 CONTENTS HISTORY OF THE LFS IN THE UK SECTION 1 - THE LFS IN GREAT BRITAIN..........................................................................................1 LFS 1973-1983.......................................................................................................................................................1 ANNUAL LFS 1984-1991...........................................................................................................................................1 QUARTERLY LFS FROM SPRING 1992.........................................................................................................................1 LFS QUARTERS ......................................................................................................................................................2 EARNINGS FROM EMPLOYMENT QUESTIONS FROM WINTER 1992/93 ..............................................................................2 UK ESTIMATES FROM 1994/5 ....................................................................................................................................3 EARNINGS QUESTIONS FROM SPRING 1997 ................................................................................................................3 MONTHLY PUBLICATION FROM WINTER 1997/8............................................................................................................3 LOCAL LABOUR FORCE SURVEY AND WELSH LABOUR FORCE SURVEY ...........................................................................3 SECTION 2 - THE LFS IN NORTHERN IRELAND ................................................................................4 SAMPLE, DESIGN, QUESTIONNAIRE, FIELDWORK AND PROCESSING SECTION 3 - SAMPLE DESIGN.............................................................................................................5 SURVEY DESIGN OF THE LFS .....................................................................................................................................5 SIZE OF THE SELECTED SAMPLE OF ADDRESSES.........................................................................................................5 SURVEY METHODOLOGY..........................................................................................................................................5 COVERAGE AND SAMPLE SELECTION.........................................................................................................................6 SAMPLING FRAMES .................................................................................................................................................7 NON-PRIVATE HOUSEHOLDS (COMMUNAL ESTABLISHMENTS) IN THE LFS........................................................................8 SECTION 4 - THE QUESTIONNAIRE ..................................................................................................12 MANAGEMENT OF THE LFS QUESTIONNAIRE .............................................................................................................12 QUESTIONNAIRE DESIGN AND STRUCTURE...............................................................................................................12 SECTION 5 - FIELDWORK...................................................................................................................13 FIELD MANAGEMENT AND THE LFS WAVE STRUCTURE................................................................................................13 FIELD MANAGEMENT AND THE LFS SURVEY DESIGN ...................................................................................................13 DEPENDENT INTERVIEWING AT RECALL WAVES.........................................................................................................14 REQUIREMENTS FOR ANSWERS TO QUESTIONS ........................................................................................................14 PROXY INTERVIEWS ..............................................................................................................................................15 COMPUTER ASSISTED INTERVIEWING (CAI) ..............................................................................................................17 RESPONSE RATES ................................................................................................................................................18 QUALITY CONTROL OF FIELDWORK..........................................................................................................................22 NON-ENGLISH SPEAKING RESPONDENTS .................................................................................................................22 SECTION 6 - CODING AND PROCESSING THE DATA ....................................................................23 CODING...............................................................................................................................................................23 DERIVED VARIABLES .............................................................................................................................................24 DATA CHECKING...................................................................................................................................................24 DATA QUALITY SECTION 7- NON-SAMPLING ERRORS.............................................................................................26 MEASURING ACCURACY.........................................................................................................................................26 TYPES OF NON-SAMPLING ERROR...........................................................................................................................28 ERRORS OF NON-OBSERVATION .............................................................................................................................29 MEASUREMENT ERROR .........................................................................................................................................30 February 2003 i Labour Force Survey User Guide – Volume 1: Background & Methodology PROCESSING ERROR ............................................................................................................................................31 SECTION 8 - SAMPLING ERRORS AND CONFIDENCE INTERVALS ..............................................33 NON-SAMPLING ERRORS AND SAMPLING ERRORS .....................................................................................................33 MEASURING PRECISION USING STANDARD ERRORS ...................................................................................................33 STANDARD ERRORS AND CONFIDENCE INTERVALS OF ESTIMATES OF LEVELS ...............................................................34 STANDARD ERRORS AND CONFIDENCE INTERVALS OF ESTIMATES OF CHANGES ............................................................36 PUBLICATION THRESHOLDS ...................................................................................................................................37 PUBLICATION THRESHOLDS FOR EARNINGS DATA......................................................................................................38 CALCULATING CONFIDENCE INTERVALS FOR EARNINGS PERCENTILES USING QUANVERT................................................38 SECTION 9 - NON-RESPONSE ...........................................................................................................40 CENSUS-LINKED STUDY - BACKGROUND AND METHODOLOGY.....................................................................................40 CENSUS-LINKED STUDY - SUMMARY OF RESULTS......................................................................................................41 QUESTION SPECIFIC NON-RESPONSE RATES - PERCENTAGE NON-RESPONSE..............................................................43 SECTION 10 - WEIGHTING THE LFS SAMPLE USING POPULATION ESTIMATES.......................44 WEIGHTING THE MAIN LFS......................................................................................................................................44 WEIGHTING THE EARNINGS DATA............................................................................................................................48 SECTION 11 - REPORT ON PROXY RESPONSE STUDY BASED ON LFS QUESTIONS...............50 INTRODUCTION ....................................................................................................................................................50 RESULTS: COMPARISON OF PROXY AND PERSONAL INFORMATION...............................................................................52 DISCUSSION OF FINDINGS ......................................................................................................................................54 CONCLUSION .......................................................................................................................................................59 SECTION 12 - IMPUTATION IN THE LFS............................................................................................60 IMPUTATION AND NON-RESPONDING DNAS ...............................................................................................................60 IMPUTATION OF ETHNICITY IN SPRING 2001...............................................................................................................62