SMALL AREA ESTIMATION FOR CITY STATISTICS Prepared by Ivana Levacic – Classification, Sampling and Statistical Methods Department Presented by Branko Crkvencic – Spatial Statistical Register Department

Sub national statistics grant is not first time that CBS implemented Small area estimation Already used for poverty mapping where we have estimated poverty rates for each municipality in Croatia Labour Force Survey is designed to provide reliable estimates of finite population parameters only for large domains (whole country and eventually NUTS2 region We need another solution

Solution is to apply small area estimation method to estimate labour status for the 556 Croatian cities / municipalities at annual frequency These estimates are based on 2017 Labour Force Survey data For improvement of direct survey estimates CBS used a basic area level Fay-Herriot model The Fay – Herriot model (Fay and Herriot 1979) has two components: a sampling model for the direct survey estimates and a linking model for the small area parameters of interest

Labour Force Survey in Croatia Basic concepts and definitions Currently active population or the labour force consists of persons whose activity status in the reference week is either employed or unemployed Persons in employment are those who were engaged in any work for payment in cash or kind during the reference week. Those are employees, the self-employed, and family members who are helping in some kind of family business or some other kind of gainful activity, as well as persons who worked on contract, for direct payment in cash or kind

Labour Force Survey in Croatia The survey covers all persons who worked for at least one hour in the reference period, irrespective of their formal status or means of payment. This means that a retired person, a student or a housewife can also be classified as employed. Persons in employment are also those who were absent from work during the reference week but had a job to return to with the same employer after the reason for absence no longer existed.

Labour Force Survey in Croatia Unemployed persons are those who meet the following three criteria: a) In the reference period did not work for payment in cash b) Were actively seeking work during four weeks prior to the Survey c) Were currently available for work within the next two weeks

Labour Force Survey in Croatia LFS is based on the random sample of private households Sample consists of four separately selected subsamples, rotation groups or panels Sample frame is stratified in four strata at NUTS 2 level and further separated into urban and rural parts

Labour Force Survey in Croatia Before selecting the sample, the so-called segments are formed Segments are territorial units formed by grouping of one or several neighbouring enumeration districts which were established for the purpose of carrying out the 2011 Population Census Weighting procedure is carried out in order to calculate the estimate for the whole household population and this procedure provides for the compensation of the design and sample size impact as well as the impact of the non-response of households to the Survey

Auxiliary Information Success of increasing the precision of the domain estimates with the area level model depends on the availability of correlated auxiliary information Model base estimates involve known population totals (auxiliary data) and estimates of the regression between the variable of interest and the auxiliary data across the small areas; area level models are based on direct survey estimates aggregated from the unit level data and related area level auxiliary variables obtained from surveys and/or administrative records such as censuses or registers

Employment The selected variables for estimated employment are: Number of working – age population in 2011 Number of persons employed in legal entities in 2016 Number of persons with high education in 2011

Labour Force Survey map

Employment This graph shows comparison of estimated absolute number of persons in employment between direct estimate from survey and collected data (in red) and employment totals estimated using small area estimation method (in green). Totals are estimated for all municipalities in Croatia, so in red line there is no estimates for all municipalities – only for municipalities that are in sample.

Employment On this graph we can see comparison of coefficients of variation (CVs – relative sampling errors) for estimated employment totals for direct estimates from survey (collected data) in red and for estimated employment totals using small area estimation method in green. It can be concluded that SAE method decreased sampling errors (CVs) for estimated data for 7 cities. Hence they are more reliable and accurate using SAE methods than direct estimates from survey data.

Unemployment The selected variables for estimated unemployment are: Labour force in 2011 Poverty rate in 2011

Unemployment This graph shows comparison of estimated absolute number of unemployed persons between direct estimates from survey and collected data (in red) and unemployment totals estimated using small area estimation method (in green). Totals are estimated for all municipalities in Croatia using SAE method although there is no direct estimates from survey data as not all municipalities were included in LFS 2017 sample.

Unemployment On this graph we can see comparison of coefficients of variation (CVs – relative sampling errors) for estimated number of unemployed persons between ones for direct estimates from survey (collected data) in red and the ones for estimated unemployment totals using small area estimation method in green. It can be concluded that SAE method decreased sampling errors (CVs) of estimated unemployment totals for 7 cities. Hence they are more reliable and accurate using SAE methods than direct estimates from survey data.

Labour force For the estimated labour force a forward stepwise procedure is carried out to select auxiliary variables. The selected variables for estimated unemployment are: Number of employed in 2011 Poverty rate in 2011

Labour force This graph shows comparison of estimated absolute number of labour force between direct estimates from survey and collected data (in red) and labour force totals estimated using small area estimation method (in green). Totals are estimated for all municipalities in Croatia using SAE method although there is no direct estimates from survey data as not all municipalities were included in LFS 2017 sample.

Labour force On this graph we can see comparison of coefficients of variation (CVs – relative sampling errors) for estimated number of labour force totals between ones for direct estimates from survey (collected data) in red and ones for estimated labour force totals using small area estimation method in green. It can be concluded that SAE method decreased sampling errors (CVs) of estimated labour force totals for 7 cities. Hence they are more reliable and accurate using SAE methods than using direct estimates from survey data.

crkvencicb@dzs.hr