C onference on Data Quality for International Organisations ( Rome, Italy, 7-8 July 2008)

1. Conference on Data Qualityfor International Organisations(Rome, Italy, 7-8 July 2008) Session 1: Assessment of data quality The example of the Wages part in the ILO Yearbook of Labour Statistics (http://laborsta.ilo.org) Le Anh Hua (hua@ilo.org) Bureau of Statistics International Labour Office Geneva, Switzerland

2. Overview of the presentation • The ILO tools for ensuring quality • Some statistics in Laborsta • Data collection instruments • What we do to check the quality of the statistics reported • Forms of dissemination • Measurements linked to the statistics • Points of concern for discussion

3. ILO tools for ensuring quality • Set of procedures to ensure consistency, timeliness and coherence • Standardised questionnaires pre-filled with earlier statistics, and with instructions and classifications • Methodological descriptions • Correspondence and follow up with countries • Database documentation

4. Wage statistics in Laborsta(last observation in 2004 or later)

5. Data collection instruments • Questionnaires, incl. instructions and annexes with classifications • On the following slides • 1st page with contact information • Overview of concepts, units, coverage, source • Table 5A, by ISIC tabulation categories • Table 5B, by divisions of manufacturing • Table 5C, for agricultural activities

10. Assessment criteria • Official statistics? • Source, coverage, time unit, currency units • Divergence from main concepts • Upward/downward variation from trend • New series v. old series • National websites & national publications • Metadata available facilitate quality control checks

11. Variation from trends • Are the newly submitted values reasonable? • Change in currency ? • CPI ? • Typing mistake in the reported figures ? • Data identified as possible error • corrected from original or supplementary information • Enquiry with data supplier for correction • If unresolved: not disseminated.

12. Old series v. new series Possible situations • Old series not updated, but new series provided • Old series updated, and new series provided • Existing series not updated • Tables returned empty

13. Validation tests • consistency across tables: average for D (manufacturing) in 5A should be identical to “total” in 5B • consistency within tables: average for total (♀+♂)≤ maximum ♀ & ♂ , and ≥ minimum ♀ & ♂ • implausible values: average for Total (♀+ ♂)≠ arithmetic mean (♀+♂)(except in the case of an identical wage rate for men and women) • If break in series then note shown at the year • Coherence between source of series and source in “Sources & Methods”

14. Forms of dissemination • http://laborsta.ilo.org • Statistical series and methodological information • Display on screen and downloadable files • ILO Yearbook of Labour statistics • Sources & methods publications • Volume 2: Establishment Surveys: Employment, Wages, Hours of Work and Labour Cost • Volume 4: Administrative Records and Related Sources: Employment, Unemployment, Wages and Hours of Work

15. Measurements linked to the statistics • No. of hits on Laborsta • No. of requests by email/telephone. • No. of series updated each year • No. of responses processed each year • User satisfaction survey on the web • Problems observed and resolved • Running review of lessons learned and ways to make the processes more efficient

16. Points of concern for discussion • How to « fill the gaps » in the available series ? • What could be done to improve the response rates ? • Should we also consider using non-official statistics ? • What are the main quality concerns for an international gathering and dissemination of statistics from countries ? • Country coverage (geographical, persons) ? • Time series length and coherence? • Comparability between countries ? • Can the quality of the series be quantitatively expressed ?