1. C onference on Data Quality for 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) Table 5A by economic activity 91 countries142 time series 4000 time lines Table 5B manufacturing 91 countries135 time series 4600 time lines

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 CostVolume 2: Establishment Surveys: Employment, Wages, Hours of Work and Labour Cost –Volume 4: Administrative Records and Related Sources: Employment, Unemployment, Wages and Hours of WorkVolume 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 ?