Handbook on Precision Requirements and Variance Estimation for ESS Household Surveys Denisa Florescu, Eurostat European Conference on Quality in Official Statistics Vienna, 3-5 June 2014

2 Contents 1.Standard formulation of precision requirements 2.Variance estimation methods and tools Good and bad practices 3.Approaches to compute standard errors for national and EU statistics 4.Guidance to assess the compliance to the requirements

3 Standard formulation of precision requirements Two strategies Precision thresholds to be met by a few main target national indicators Minimum effective sample sizes to be ensured by National Statistical Institutes Quality of the output Recommended for regulations They ensure satisfactory precision for a few indicators, too Design requirements, not quality of the output

4 Standard formulation of precision requirements Precision measures geared to the type of statistics Relative precision measuresAbsolute precision measures recommended for: Totals and means of continuous variables Proportions Ratios and changes close to 0

5 Impact of proportion on the minimum sample size needed to achieve a coefficient of variation of 5 %, under simple random sampling

6 Standard formulation of precision requirements For EU regulations, for: proportions overall national estimates and estimates of national breakdowns estimates of level and net changes of estimates of level Some versions e.g. precision expressed as model function of estimated proportions

7 Evaluation of methods and recommendations using various criteria e.g.: Applicability to sampling designs and types of statistics: choice guided by a developed matrix: Types of statistics Sampling designs LinearRatiosNon-linear, smooth Non-smooth …………… …………… Suitable methods Unsuitable methods References Variance estimation methods

8 Type of dataApproachMethods AggregatedDecentralised in NSIsVarious Integrated burden shared by NSIs and Eurostat Generalised variance functions parameters provided by NSIs Approaches to compute standard errors for national and European statistics

9 Type of dataApproachMethods MicrodataIntegrated burden shared by NSIs and Eurostat Replication methods Fully centralized burden in Eurostat Replication methods Approaches to compute standard errors for national and European statistics

10 Guidance to assess compliance to requirements  Principles of transparency and tolerance  3 strategies:  Use of integrated or fully centralised approach in Eurostat  Trace systematic deviations on the basis of quality reports (metadata template proposed)  Fixed normative rules agreed in advance between NSIs and Eurostat

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