1. Weighting issues in EU-LFS
Carlo Lucarelli – Frank Espelage LFS Workshop May 2018, Reykjavik
Eurostat

2. Background
Council Regulation (EC) No 577/98 on the EU-LFS: "The weighting factors are calculated taking into account in particular the probability of selection and external data relating to the distribution of the population being surveyed, by sex, age (five-year age groups) and region (NUTS 2 level), where such external data are held to be sufficiently reliable by the Member States concerned (Article 3(5))".

3. The state of play Two main methods are used: Post-stratification
Calibration
Variables used by countries in 2016 (33 countries):
Sex: All
NUTS 2: All
Age (5-years age groups): all except DE, EL, SI
Nationality: 11 (DK, DE, EE, IE, ES, IT, LU, NL, AT, SE, CH)
Urban/rural: 10 (BG, EE, HR, CY, LV, LT, HU, PL, RO, TR)
Employment/unemployment register info: 8 (DK, LV, NL, AT, FI, SE, NO, CH)

4. Specific issues Sub-sampling and wave approach Household weighting
Ad-hoc module weighting
Use of registers in weighting

5. Sub-sampling and wave approach (1/3)
Commission Regulation No 377/2008: "The word ‘yearly’ […] identifies structural variables which optionally need only to be surveyed as annual averages, using a sub-sample of independent observations with reference to 52 weeks, rather than as quarterly averages. Core variables to be surveyed each quarter are identified as ‘quarterly’. […] Consistency between annual sub-sample totals and full-sample annual averages shall be ensured for employment, unemployment and inactive population by sex and for the following age groups: 15 to 24, 25 to 34, 35 to 44, 45 to 54, 55 +".

6. Sub-sampling and wave approach (2/3)
Countries adopting subsampling in 2016/2017
*Information refers to 2017 ** Information refers to 2016
Consistency requirements generally fulfilled, some issues in CZ, FR, LU and NL
The IESS regulation introduces just minor changes to sub- sampling for the core LFS (minimum size of the subsample, one age group for consistency requirements). Core LFS sub-sampling remains an option.
Subsampling
Number of countries
Countries
Structural variables * 12
BE, BG, CZ, ES, FR, LV, LU, NL, FI, UK, NO, CH
Ad hoc modules ** 16
BG, CZ, DK, DE, ES, FR, LV, LU, MT, NL, AT, FI, SE, UK, NO, CH
Household * 4
DK, LU, FI, SE

7. Sub-sampling and wave approach (3/3)
Quarterly weighting: by sex, 5-year age groups, region Yearly weighting: 'similar' in most countries plus consistency Does it mean 'by ILOSTAT, sex, age, region' all together? Example: for each region it would mean 3 x 2 x 5 = 30 constraints (required 10-year age groups) 3 x 2 x 20 = 120 constraints (full coverage 5-year age groups) Eurostat analysis of available information and data: difficult to decide whether deviations at regional level are due to non-inclusion of region or due to (non-)convergence issues…

8. Household weighting (1/2)
The current LFS regulations do not say anything on household weighting, but LFS based household estimates are disseminated by Eurostat and also by several countries at national level.
Household weighting characteristics in 2016
Weighting features
Number of countries
Countries
Countries who use standard core weighting procedure for computing both individual and household weights
 18
CZ, DE, DK, EE, ES, HR, IT, CY, LT, LV, HU, NL, AT, PT, RO, SI, FI,TR
Different calibration for core and household weights  4
FI, SE, UK, NO
No household weights 5
BG, EL, IE, MT, SK
Use of information at household level in weighting procedure (number of households, household size, household type or composition) 20
BE, CZ, DK, ES, FR, HR, IT, CY, LT, LU, HU, NL, AT, PL, RO, FI, UK, NO, MK, TR

9. Household weighting (2/2)
Requirements for household weighting might become part of the future LFS implementing act under IESS:
At household level:
Households info (number and size) in household weighting
Average household weight number of households in the country
At individual level:
Weighted number of records total population (i.e. 0+)
Weighted number of adults adults in the population
ILO labour status distribution full sample annual average results (by sex, age group…)
General recommendation: equal weights for all persons in the household.

10. Ad-hoc module weighting (1/2)
The current LFS regulations do not say anything on ad-hoc module weighting
Ad-hoc module weighting in 2016
Ad-hoc module weights
Number of countries
Countries
Quarterly core weights 15
BE, DK, IE, EL, HR, IT, CY, LV, LT, HU, PT, RO, SI, SK, TR
Annual sub-sample core weights  8
BG, CZ, ES, LU, NL, FI, UK, NO
Specific for AHM 8
DE, EE, FR, MT, AT, PL, SE, CH

11. Ad-hoc module weighting (2/2)
The regular modules under IESS will be the only blocks of variables for which yearly sub-sampling will become compulsory.
It is envisaged to define weighting and consistency requirements for the regular modules and ad-hoc subjects in line with the approach for yearly sub-sampling:
In particular:
Weighting taking the distribution of the population being surveyed by sex and age group(s) into account
Consistency between annual module sub-sample totals and full- sample annual averages for employment, unemployment and inactive population by sex and age group(s).

12. Use of registers in weighting (1/2)
In the current legislation there are no clear rules on the use of administrative data in the weighting. Council Regulation (EC) No 577/98 states "whereas the use of existing administrative sources should be encouraged insofar as they can usefully supplement the information obtained through interviews or serve as a sampling basis" but it does not directly refer to weighting.
Use of registers in weighting in 2017
Registers info
Number of countries
Countries
Use of non-demographic administrative data in weighting procedures 9
DK, FR, LV, NL, AT, FI, SE, NO, CH
- from employment registers  5
NL, AT, SE, NO, CH
- from unemployment registers 8
DK, LV, NL, AT, FI, SE, NO, CH
- from income/tax register 5
FR, LV, NL, NO, CH

13. Use of registers in weighting (2/2)
Countries using registers: future improvements
Other countries: interested in the introduction
Under IESS, the use of registers is encouraged as well as methods based on integration of different sources, as far as these techniques can enhance the quality or reduce the costs of the survey.
However, any use of register employment or unemployment in the weighting must not impact on the harmonised measurement of the ILO labour force status in the LFS.

14. Conclusion
The weighting procedure is an important and sensitive step in the whole process of LFS data production. The future LFS implementing regulation(s) will have to take these aspects into account and provide a general framework to which national weighting approaches should adapt in order to enhance the comparability between labour market estimates of different countries. The future LFS implementing act(s) will include more weighting rules than in the past, explicitly adding module and household weighting requirements and further consistency requirements across sub-samples.