An assessment of the robustness of weights in the Famille et Employeurs survey

1. An assessment of the robustness of weights in the Famille et Employeurs survey Nicolas Razafindratsima (razafind@ined.fr) & Elisabeth Morand (Elisabeth.Morand@ined.fr) INED European Conference on Quality in Official Statistics, Rome, July 2008

2. Outline • Introduction • The Famille et Employeurs survey • Methodology of weights calculations • Results • Conclusion

3. Introduction • In indirect sampling : the generalized weight share method (Lavallée, 2002 & 2007) is a simple and easy strategy to produce unbiased estimations • Objective of this study : to expose the implementation of this method for the Familles et Employeurs survey (Ined/Insee, 2004-2005) : difficulties, and robustness of the weights obtained.

4. The Familles et Employeurs survey • Main purpose : to study professional and family life conciliation: - from the employees point of view - from the employers point of view • Can behaviours within the family be explained through employers rules and characteristics? • A matched survey: employee  employers

5. The household survey • Sampling strategy : - a sample of 11 719 dwellings drawn from the INSEE master sample  6 167 of them answered - interview of 1 or 2 individuals, aged 20-49, in each household (random sampling if >2)  9 547 respondents • Face to face interview. Questionnaire on demographic events (birth, unions), family life organization, etc., in relation to individuals professional context

6. The establishment survey • Target : Establishments of 20 employees or more • Individuals respondents were asked to give their employers name, address, national identification number as well as their size and sector. • A self administered questionnaire was sent to the establishments. Possibility to answer by paper or by the Internet. 2 673 respondents.

7. Weighting methodology • The basic for establishments weighting methodology : the generalized weight share method Where : Wi=weight of establishment i Wj=weight of individual j (those in the sample) Li= number of eligible employees (aged 20-49) in the establishment i

8. Weighting methodology • Difficulties : - the choice of individuals weight (non-response, calibration) - the estimation of the number of employees aged 20-49 in the establishment [- establishment non-responses]

9. Weighting the sample of individuals • Non response variations : • At the household level (non-response higher in urban areas, for collective dwellings, etc.) • At the individual level (non-response higher for males, single persons, less-educated people, etc.) • Non-response adjustments : • At the household level : using corrective response rates within response homogeneity groups • At the individual level : calibration (on Labor force survey data) - on a single variable : gender*age - or on 7 variables : gender*age, employment status, nationality, region, highest diploma, urbanization status, household size

10. Distribution of individuals weights

11. Estimation of the number of eligible employees (aged 20-49) • Number of employees (total and by age groups) asked in the establishment questionnaire • But number of 20-49 not available for 16% of the establishments (item non-response) • Imputation of number of 20-49 when non-response : using coefficients of a regression model among respondents, linking nb of 20-49 to total (one model by activity sector) • For 2/3 of the establishments, total size is also available through the SIRENE directory. Allows an other estimation of 20-49 number for evaluation purposes

12. Distribution of total size

13. Distribution of number of 20-49

14. Summary of the options for establishments weighting Employees weight=establishment weight*nb of employees

15. Distribution of establishment weights

16. Distribution of employees weight

17. Percentage of establishments having a crèche

18. Percentage of employees working in an establishment with a crèche

19. Conclusion • Weight sharing method : • A simple and easy to implement method • However, difficult to implement in the Famille et Employeurs survey, due to : • non-responses on the ‘link’ variable • High dispersion of the size variable • More sensitive to the link variable than on specification of the individual weights • All the computed weights present great variability • Weight trimming may improve precision at the establishment level, but fails to do so at the employees level

20. References • Lavallée, P. (2002) : Le sondage indirect, ou la méthode généralise du partage des poids, Bruxelles, Presses de l’université libre de Bruxelles et Paris, Ellipses, 242 pages. • Lavallée, P. (2007) : Indirect sampling, New York, Springer (Springer series in statistics), 245 pages.

21. Thank you for your attention !