1. LFS series breaks with the adoption of the IESS FR How is Statistics Portugal planning to tackle the issue?
13th Workshop on Labour Force Survey Methodology
Session 3: Series Breaks
Sónia Torres
Statistics Portugal / Labour Market Statistics Unit
Reykjavik, 18th May, 2018

2. « « The LFS transition into the new regime in Portugal
1. Changes to be introduced in 2021
Changes directly implied by the IESS FR adoption (all countries):
New questionnaire: variables design & frequency (e.g. redefinition of current variables; core/standardized variables; new variables; regular modules) + flowcharts and model questions for the labour status measurement.
New concepts: although the main concepts (E and U) do not change in substance, the 19th ICLS Resolution provided more clear specifications (e.g. coverage; inclusions/exclusions).
Expected sizeable change in Portugal, as the subsistence agriculture will be no longer considered as employment. In 2017: 3.4% of total employment; 53% of employment in section A.

3. « « The LFS transition into the new regime in Portugal
1. Changes to be introduced in 2021 (cont.)
Statistics Portugal will take the opportunity to introduce other changes (to reduce the respondents’ burden and to concentrate all changes at once):
Wave approach: large questionnaire (all variables) in the 1st interview (CAPI) + simple questionnaire (quarterly variables) in the 2nd-6th interviews (CAWI or CATI), under certain conditions.
Dependent interviewing (reinforcement): from a dozen of demographic variables to a larger list of non-demographic variables (based on testing) + simplified rules for ind. 75+.
Web interviewing (alongside with CAPI and CATI): in the 2nd-6th interviews. In the 1st interview (CAPI), the interviewer “teaches” how to fill in the LFS questionnaire and informs about its smaller size in the following quarters.

4. « « The LFS transition into the new regime in Portugal
2. Statistics Portugal strategy to tackle the series break
All changes will likely translate into a series break in the Portuguese LFS estimates (like it did in 2011).
Need to provide users with (at least for the main indicators):
Linking factors (to understand the break).
Back-calculated series (for short-term analyses).
Also required by Eurostat for 14 indicators (E and U by sex and age group) + other indicators on a voluntary basis, until December Up to a maximum of 1 annual + 4 quarterly factors per indicator.
And to publish both in the day of dissemination of the new series results (1Q2021, in May 2021) (to be useful).

5. « « The LFS transition into the new regime in Portugal
3. The parallel sample design
Set up of a Task Force, which compared several alternatives to compute accurate linking factors (pros and cons of each):
Time-series models to make forecasts or nowcasts with external data → Not feasible in Portugal:
LFS series patterns not easy to forecast.
Administrative data not available for all variables.
Risk of transition into the new regime (questionnaire and collection mode) in 1Q2021 with the same sample.
Use of a parallel sample, from 2Q2020 to 4Q2020, alongside with the current LFS (core LFS) → Diagram next slide

6. « The LFS transition into the new regime in Portugal
CAPI: Computer Assisted Personal Interviewing
CATI: Computer Assisted Telephone Interviewing
WI: Web Interviewing
Ii: interview [i = 1 to 6]
Qjk: questionnaire [j = 1 (current) or 2 (new); k = L (large: all variables) or S (small: quarterly variables)]

7. « « The LFS transition into the new regime in Portugal
3. The parallel sample design: characteristics, advantages and drawbacks
New sample (another source of break): the one that will proceed (smoothly) into the new regime in 1Q2021.
Big size: total of 12 rotations (5 in CAPI); 2 almost complete quarters → Expensive solution.
Start in 2Q2020. Why?
To min. costs (vis-a-vis 4Q2019 or 1Q2020).
To min. the Rotation Group Bias (vis-a-vis 3Q2020 or 4Q2020).
To provide enough time to conclude all upstream tasks (e.g. questionnaire; wave approach; dependent interviewing; implement and test IT tools).

8. « « The LFS transition into the new regime in Portugal
3. The parallel sample design: characteristics, advantages and drawbacks (cont.)
Linking factors calculation flexibility: as many as needed, by using 2 almost complete quarters (3Q2020 and 4Q2020).
No impact in the LFS core results during the transition period.
Independence of the LFS core sample (respondents must also have never replied to LFS questionnaires before).
Data collection modes (CAPI/CATI/CAWI), rules for proxy, imputation rules and weighting = LFS under the IESS FR (1Q2021).
Hard to collect in 2020 (Census 2021 fieldwork preparation).
Implications for the MUR dissemination in 5 months.

9. « « The LFS transition into the new regime in Portugal
4. The linking factors calculation
By differences between the estimates obtained from the parallel sample and the estimates obtained from the LFS core sample → Justified by the similar characteristics of both samples, except for the changes to be introduced.
For 2 quarters (3Q2020 and 4Q2020), then averaged.
1 factor per indicator (variable/breakdown), to avoid complexities in linking the series & interpreting the results and the need to run a parallel sample for at least 4 quarters.
The same factor will be applied to all quarters and years in the back-calculation exercise.

10. « « The LFS transition into the new regime in Portugal
5. Communication strategy
1Q2021 results to be published in May 2021, alongside with:
The linking factors for a selection of indicators.
The back-calculated series for a selection of indicators.
A methodological paper describing both the changes introduced in the LFS and the methodology followed to calculate the factors.
A briefing with journalists (to be evaluated).
Meetings with main LFS users (e.g. Ministry of Employment; Ministry of Economy; Bank of Portugal; National Accounts Department; Statistics Council) during the transition process.
Advance information note (in December 2020) for general LFS users.

11. « « The 2011 LFS series break in Portugal
6. Notes regarding the 2011 LFS series break
In May 2011, Statistics Portugal released the results of a new LFS series, starting in 1Q2011 (break with the 1Q1998-4Q series).
Main change: mixed mode data collection (from CAPI to CAPI+CATI) → Deep revision in the questionnaire.
Purposes of the change: sustain the decrease in response rates (e.g. by reducing the interviewing time and by offering a friendlier interviewing mode); reduce costs; improve efficiency (e.g. interviewers/supervisors procedures; data collection management; monitoring tools; HOMECATI).
All other characteristics unchanged: sample size and design; representativeness; weighting; rotation pattern; and concepts.

12. « « The 2011 LFS series break in Portugal
6. Notes regarding the 2011 LFS series break
Long-lasting process, involving:
Several Departments at Statistics Portugal and an external consultant.
Study visits to 2 countries (Spain and Finland).
Parallel sample in place for 1 year (24 rotations): to test and implement the new CATI logistic, to test several effects, and to calculate linking factors, without harming the LFS core.
Meetings with the LFS main users.
Process and results generally welcomed by users, although too expensive and time-consuming.
Impacts: ↓ E, ↑ U, and ↑ UR (+1.1 p.p.).

13. The 2011 and 2021 LFS series break compared