Information Note - Break in Time Series SILC 2020

The primary focus of the Survey on Income and Living Conditions (SILC) is the collection of information on the income and living conditions of different types of households in Ireland, in order to derive indicators on poverty, deprivation and social exclusion. It is a voluntary (for selected households) survey of private households. The survey has been running annually in Ireland since 2003. 

In 2021 the European legislative basis (Regulation No 1177/2003) for the production of statistics on income and living conditions has been repealed by Regulation 2019/1700. This new framework regulation establishes a common framework for European statistics relating to persons and households, based on data at individual level collected by samples. In order to meet the requirements of the new regulation, the Central Statistics Office (CSO) introduced changes to many SILC business processes. These changes have resulted in a break in the SILC time series for 2020. 

Main sources of break in SILC time series 

Change in data collection period 

Under Regulation No 1177/2003 the SILC cross sectional data transmission deadline from the Member States to the Commission (Eurostat) for a data collection year T was November 30 of year T+1. From 2022, under Regulation 2019/1700 there will be improved timeliness, with shorter deadlines for SILC data submission, the new transmission deadline being December 31 of year T (the current survey year). To meet the new transmission deadline, the CSO changed the data collection period from continuously throughout the year to the first 6 months of the year. 

Change in SILC income reference period 

Up until 2019 the SILC income reference period was the 12-month period immediately preceding the sample household's interview date. This resulted in a 24-month income reference period for each annual SILC survey. Commencing with the 2020 SILC publication, the SILC income reference period will be T-1. 

Standardised variables 

Eurostat issued implementing guidelines for 38 social variables common to the several datasets under Regulation (EU) 2019/1700.  The standardised variables are  

(1) Sex  

(2) Age in completed years  

(3) Household grid  

(4) Partners living in the same household   

(5) Household size  

(6) Household type   

(7) Tenure status of the household 

(8) Main activity status (self-defined)  

(9) Full- or part-time main job (self-defined)   

(10) Permanency of main job   

(11) Educational attainment level   

(12) Participation in formal education and training (student or apprentice) in   

(13) Level of the current or most recent formal education or training activity  

(14) Country of birth  

(15) Country of main citizenship  

(16) Country of birth of the father  

(17) Country of birth of the mother  

(18) Country of residence   

(19) Duration of stay in the country of residence in completed years   

(20) Region of residence  

(21) Degree of urbanisation 

(22) Status in employment in main job  

(23) Economic activity of the local unit for main job  

(24) Occupation in main job  

(25) Self-perceived general health  

(26) Long-standing health problem   

(27) Limitation in activities because of health problems 

(28) Net current monthly household income   

(29) Existence of previous employment experience   

(30) Size of the local unit for main job 

(31) Supervisory responsibilities in main job   

(32) Year in which the person started working for his or her current employer or as self-employed in main job  

(33) Year when the highest level of education was successfully completed   

(34) Field of the highest level of education successfully completed  

(35) Interviewing mode used 

(36) Nature of participation in the survey  

(37) Stratum 

(38) Primary sampling unit 

In order to satisfy implementing guidelines related to these standardised variables, some questions in the 2020 SILC questionnaire were changed. For example, standardised variable No 29 ‘Existence of previous employment experience’ has now 3 answer modalities with an associated definition for ‘occasional work’

(1) Person has never been in employment
(2) Person has employment experience limited to occasional work
(3) Person has employment experience other than occasional work

In 2020 changes were made to questions on ‘previous employment experience’ in the national SILC questionnaire. These changes were required to ensure compliance with the implementing guidelines.

Definition of a Household 

Up until 2020 in defining a ‘household’, the national SILC used an 'address' concept (i.e. all persons living at the same address treated as a single household).

From 2020 the national SILC definition of a household will use a shared income and expenditure concept. Flatmates or housemates that don’t share expenditure will now be considered as separate households, and students living away from home and substantially supported by their parents will be considered members of the parent household.

Changes to income definitions 

Under regulation No 1177/2003 the core SILC output variable PY030 (Employer's social insurance contribution) included some discretionary employer contributions e.g. employers’ contributions to private health insurance, employers’ contributions to life insurance and employers' contributions to income continuance plans. Under Regulation 2019/1700 these discretionary contributions will not be included in PY030. These contributions will instead be reported as PY020 (non-cash employee income).  

Up until SILC 2019 when calculating disposable income (national definition) PY030 (employer's social insurance contributions) was deducted from gross household income (which included PY030). With the changes described in the above paragraph from 2020 national disposable income will now include values for employers' contributions to private health insurance, to life insurance and to income continuance plans as these contributions will no longer be included in PY030 as they are now considered as non-cash employee income. 
 
Up until SILC 2019 when calculating disposable income (national definition) regular taxes on wealth (Local Property Tax (LPT) was not deducted from gross household income. From 2020 LPT will be deducted from gross household income when calculating net disposable income.  

Up until SILC 2019, capital gains income and tax were not accounted for in SILC.  From 2020, capital gains income will be included in income and the associated tax will be deducted when calculating net disposable income. 
 
Up until SILC 2019 when calculating household disposable income, employee and self-employed individual contributions to occupational and private pension plans were not deducted from gross household income, while benefits from occupational and private pensions were included when calculating household gross and disposable income.  From SILC 2020 these pension contributions are deducted when calculating net disposable income. 

In table SIA74 in PxStat (the CSO’s Data Dissemination Management System), the CSO publishes poverty indicators both ‘before’ and ‘after’ social transfers. Up until 2019, poverty indicators ‘before’ social transfers were calculated from disposable income that excluded occupational pension income in addition to other social transfers such as transfers received from the Department of Employment Affairs and Social Protection (DEASP).  From 2020, social transfers in SILC are defined as the total income received from DEASP social welfare transfers (e.g. jobseekers related payments, state pension (contributory and non-contributory), family or children related allowances), income received as education related allowances (e.g. Student Universal Support Ireland [SUSI] grants) and housing related supports which include rent supplement and Local Authority contributions to landlords of SILC respondents who are Housing Assistance Payment (HAP) or Rental Accommodation Scheme (RAS) tenants.

Change in data collection mode

In response to growing concerns related to community transmission of COVID-19 the CSO suspended all household survey fieldwork activities in mid-March 2020. SILC information before the onset of COVID-19 was collected from household members (16 years and older) by CSO interviewers, using Computer-Assisted Personal Interview (CAPI) in the respondents' homes. In March 2020 the CSO developed a SILC data collection instrument suitable for conducting SILC longitudinal interviews by telephone (Computer-Assisted Telephone Interview (CATI)).  There may be a mode effect between surveys conducted by CAPI compared with CATI interviews.  

Changes to Sampling 

Up until 2019 SILC was a four-year rotational panel survey, i.e. respondents remained in the survey for 4 consecutive years, with respondents from wave 1 to 4 in any given year. Given the new regulation puts increased demands on precision requirements for key indicators (including persistent poverty), the sample size was increased and the rotation pattern has been increased to a five-year rotation pattern. Therefore, 2020 is the first year in which five waves have been included in the survey. From 2022 the rotation pattern will be increased to six waves.

Changes to SILC Weighting and Calibration

Given the break in time series outlined above, it was decided to review and improve the weighting and calibration process. The new process adjusts the design weights to account for non-response for each wave and year. These weights are then combined for the current year and calibrated to 2020 population estimates age and sex, as well as by region, household composition and tenure status at household level.

CSO publication, 17 December 2021, 11am