UK DATA ARCHIVE: IMPORTANT STUDY INFORMATION SN:4253 - Labour Force Survey Two-Quarter Longitudinal Dataset, March - August 1994 ------------------------ New Edition Information ------------------------ For the second edition (June 2004), the depositor supplied a re-weighted version of the data file. The re-weighting has been done to bring LFS data in line with the population estimates from the 2001 Census. See under 'Useful Notes' below for full details of changes made to the data. --------------------- DATA PROCESSING NOTES --------------------- Data Archive Processing Standards --------------------------------- The data were processed to the UK Data Archive's 'A' standard. A rigorous and comprehensive series of checks was carried out to ensure the quality of the data and documentation. The most important procedures were as follows. Firstly, checks were made that the number of cases and variables matched the depositor's records. Secondly, checks were made that all variables had variable labels and all nominal (categorical) variables had value labels. Where possible, either with reference to the documentation and/or in communication with the depositor, absent labels were created. Thirdly, logical checks were performed to ensure that nominal (categorical) variables had values within the range defined (either by value labels or in the depositor's documentation). Lastly, any data or documentation that breached confidentiality rules were altered or suppressed to preserve anonymity. All notable and/or outstanding problems discovered are detailed under the 'Data and documentation problems' heading below. Data and Documentation Problems ------------------------------- No problems encountered. Useful Notes ------------ a) Weighting: For the second edition (June 2004), the depositor supplied a re-weighted version of the data file. The re-weighting has been done to bring LFS data in line with the population estimates from the 2001 Census. b)Changes to the Names of Variables: The names of some variables (listed below) have been changed as a result of the removal of the employment edit check. The variables listed may not have appeared in the previous edition of the data, but may now be included in the reweighted edition. If variables are not listed in Vol.11 of the documentation ('User Guide for Two-Quarter and Five-Quarter Datasets'), users may find Vol.3 ('Details of LFS Variables') useful. Please note that the documentation may still refer to these variables by their previous names: GORWK21 - now GORWK2R1(Region of place of work - 2nd job) ILODEFA1/ILODEFA2 - now ILODEFR1/ILODEFR2(Economic activity (reported)) INECACA1/INECACA2 - now INECACR1/INECACR2 (Economic activity (reported)) NMANAGE1/NMANAGE2 - now MANAGER1/MANAGER2(Managerial status (reported)) NMANAGE21/NMANAGE22 - now MANAG21/MANAG22 (Managerial duties 2nd job) NMPNO1/NMPNO2 - now MPNOR1/MPNOR2 (No. employees at workplace (reported)) NOYMNGE1 - now OYMNGE1 (Managerial duties 1 yr ago) NOYSTAT1 - now OYSTAT1 (Employee or self employed 1 yr ago) NSOLO1/NSOLO2 - now SOLOR1/SOLOR2 (SE w or w/out employees (reported)) NSOLO21/NSOLO22 - now SOLO21/SOLO22 (SE with or without employees(2nd job)) NSTAT1/NSTAT2 - now STATR1/STATR2 (Employment status main job (reported)) NSTAT21/NSTAT22 - now STAT21/STAT22 (Employment status (2nd job)) PUBLIC1/PUBLIC2 - now PUBLICR1/PUBLICR2 (Whether work in public or private sector) REGWK1 - now REGWKR1 (Region of place of work) REGWK21 - now REGWK2R1 (Region of place of work 2nd job) SECJMB1/SECJMB2 - now SECJMBR1/SECJMBR2 (Whether 2nd job or status in second job) Conversion of Documentation --------------------------- All electronic and paper documentation supplied with this study is normally incorporated into the UKDA User Guide (in PDF format). The conversion programs used are the latest versions of Adobe PDF Writer for electronic documentation and Adobe Paper Capture (Acrobat 'plugin' version) for paper documentation. Occasionally, some or all of the electronic documentation cannot be usefully converted to PDF (e.g. MS Excel files with wide worksheets) and this is supplied in other formats. All User Guides are fully bookmarked. Conversion of Data ------------------ Ingest format(s) of the data = SPSS portable From January 2003 onwards, almost all data conversions have been performed using software developed by the UKDA. This enables standardisation of the conversion methods and ensures optimal data quality. In addition to its own data processing/conversion functionality, this software invokes the SPSS and StatTransfer command processors to perform certain translations in a standardised and optimal way. Although data conversion is automated, all data files created are subject to inspection by a UKDA data processor. To create the format you have been supplied the data in, the following conversion will have been performed depending on the ingest format. Note that you will have only been provided the data in the format you requested. SPSS portable: If SPSS portable is not the ingest format, this format will generally either have been created via the SPSS command processor (e.g. if the ingest format is SPSS .sav, SAS, Excel, or dBase), or if the ingest format is STATA, the SPSS portable version will be created via the Stat/Transfer command processor. If the Ingest format is text (e.g. fixed width ASCII) and no setup files are provided, the UKDA will write the necessary setup files to read the data into SPSS. STATA: If STATA is not the ingest format, all STATA files will have been created from SPSS .sav format via the Stat/Transfer command processor. All files created are in STATA 6 format. Importantly, Stat/Transfer's optimisation routine is run so that variables with SPSS write formats narrower than the data (e.g. numeric variables with 10 decimal places of data formatted to FX.2) are not rounded upon conversion to STATA because they are converted to "doubles" rather than floats. User missing values are copied across into STATA where the user definition is lost), but the code exists (as opposed to being collapsed into STATA's single missing code (versions 6 and 7). Issues: Variables that include both date and time in the SPSS version, such as mm-dd-yyyy hh:mm:ss (e.g. 18-JUN-2001 13:28:00), will lose the time information and become date only. If the time information is critical, a new variable will have been created in the STATA data file by the UKDA. Tab-delimited text: If tab-delimited text is not the ingest format, tab-delimited files are created from SPSS portable files via the SPSS command processor, Excel spreadsheets, or MS Access databases. When exporting from Access data tables to tab-delimited text, the many undesirable embedded special characters allowed by access memo and text fields - tabs, carriage returns, line feds, etc., - are stripped out by the UKDA software. Issues: Date formats in SPSS are always exported to mm/dd/yyyy in tab- delimited text format - so you may note a mismatch with the documentation on such variables. Variables that include both date and time such as. mm-dd-yyyy hh:mm:ss (e.g. 18-JUN-2001 13:28:00), will lose the time information and become mm/dd/yyyy. If the time information is critical, a new variable will have been created in the tab-delimited data file by the UKDA. All users of the data in tab- delimited format are provided with the SPSS data dictionary, this being the rich text file named according to the convention _variableinformation.rtf. This contains the SPSS format information as well as the variable and value labels, and it is thereby recommended all tab-delimited data users consult this information. If the tab-delimited data were converted from MS Access, analogous 'data documenter' output will be supplied in rtf format. Likewise, the files may contain SQL setup information. MS Excel: If MS Excel is not the ingest format, Excel files are created via the SPSS command processor. The date and time issues noted under STATA and tab-delimited apply to SPSS to Excel conversion via the SPSS command processor. MS Access: Due to the substantial incompatibilities between versions of MS Access, the UKDA only make data available in MS Access format if this is the ingest format and the database contains important information in addition to the data tables (forms, queries, etc.). Other formats: Data are only made available in other formats on the rare occasion when there is no reliable method of extracting the data into a more accessible format.