Estimates for 2020 and 2021 are based on provisional and experimental versions of SILC 2020 and SILC 2021 data that have not yet been released.
As the profile of the respondents is not the same as that of non-respondents, weighting plays an important part in allowing an extrapolation to the reference population.
The weighting used for SILC 2019 is the final standard weighting, whereas that used for SILC 2020 (before or after the partial lockdown) and SILC 2021 is an experimental weighting.
The standard SILC cross-sectional weighting is usually produced roughly 10 months after the end of the field survey. Integrity checks, consolidation and the inclusion of register data (not available before March 2022 for the 2021 survey) are needed to produce this weighting. The tasks of quality control and inclusion of register data are hardly relevant to the subjective variables examined here.
A provisional and experimental weighting was calculated in order to release information as soon as possible on the impact of the COVID-19 crisis on well-being in Switzerland during the first half of 2020 and 2021. This experimental weighting includes a uniform correction for total non-response, without taking into account the specificities of the profiles. This option was due to a lack of certain auxiliary variables (of profiles) used in the standard weighting to correct for non-response.
In order to make the best possible correction for the potential bias due to total non-response, a final calibration was applied for this provisional and experimental weighting. This was applied to the same aspects as the final calibration of the standard weighting, but based on auxiliary register information from December 2019 instead of December 2020 (not available before March 2022). The experimental weighting used for COVID-19 purposes on SILC 2021 thus represents the population at the end of 2019 and not that at the end of 2020, as will be the case for the standard weighting for SILC 2021. The same time lags were applied to the experimental data for SILC 2020.
The variables used for the final calibration are all taken from registers and are as follows:
- Civil status (source SRPH)
- Sex (source SRPH)
- Nationality group- 4 groups(source SRPH)
- Type of family (source SRPH)
- Household size (SRPH)
- Major region (source SRPH)
- At risk of poverty status at 60% of median total equivalent household income (source CCO)
- Indicative of total equivalent household income < P10 (source CCO)
- Indicative of total equivalent household income < P50 (source CCO)
- Indicative of total equivalent household income < P20 (source CCO)
- Indicative of total equivalent household income > P80 (source CCO)
The latter partly overlap with the auxiliary variables used for correction for non-response in the standard weighting. The main aspects not covered are as follows:
Variables taken from registers:
- Household composition by nationality
- Type of family and number of children
- Household composition by sex
- Commune typology - 8 groups
- Nationality group- 2 groups
- Size of household’s commune
- Presence/ of supplementary benefits in household
- Number of unemployment allowances in household
- Number of disability pensions in household
- Number of old-age pensions in the household
- Number of incomes from employment in household
- Moved house (change of building) in past 2 years
- Living space per household member
Variables taken from SILC survey in wave 1 and same values used from wave 2 onwards:
- Employment status in 4 categories
- At risk of poverty status at 60% of median total equivalent household income
- Material deprivation 3 out of 9 items
- Maximum household level of education
- Interest in politics
- Rent and accommodation costs
The separation of SILC 20 respondents (before or during the partial lockdown) requires a correction for differences in the profiles of respondents at the beginning of the survey (more willing to cooperate with this statistic) and those at the end. For this reason, the net sample of respondents before 16 March was processed separately from that of respondents between 16 March and 20 June (partial lockdown in Switzerland). This means that the two sub-samples each independently correspond to the population of December 2018. There was no separation of respondents for SILC 2021.
The distribution of weights in the experimental weighting of SILC 2020-COVID-19 or SILC-2021-COVID-19 is close to that of the standard SILC 2019 weighting.
Standard income generation is not feasible within the time frame of this experimental dissemination due to the unavailability of register information. To differentiate the impact of the COVID-19 crisis by the level of household income, the estimate of total household income provided at the time of the interview was used. This estimate is given by the respondent of the Household questionnaire for the whole household. An equivalence scale has been applied to this estimate so as to compare households of different sizes. Consistency analyses between the quintiles of the total equivalent household income estimate and those of the final equivalised disposable income (SILC 2019) showed sufficient enough consistency for the household estimate to be used as the breakdown variable. It should be noted that the equivalised disposable income standard for SILC covers income in the year prior to the interview, whereas the total household income estimate is for the time of the interview.