Revision of National Accounts Time Series in the Netherlands Ruurd Schoonhoven ( RSNN@CBS.NL) Gert den Bakker, Bram de Boo, Ruben van der Helm Statistics Netherlands

Time series revisions in the Netherlands Systematic time series revisions : - after benchmark revisions of 1977, 1987, 1995, 2001 for supply and use (and I/O) tables, sector accounts and labour accounts Different methods were used …. …. with different costs (time, resources) … …. and with different quality of results How to proceed in future?

Suitability criteria for time series revisions Resources Time Quality Transparency Flexibility

Approaches to time series revisions 1. Annual backward calculation 2. Benchmark years and interpolation

I. Annual backward calculation I.1 From microdata, with new concepts and classifications (‘from scratch’) I.2 Adjustments superimposed on balanced pre-revision data I.3 Linking pre-revision (or revised) growth rates to results for revision year

II. Benchmark years and interpolation II.1 Benchmark years ‘from scratch’ II.2 Benchmark years by superposition of adjustments on balanced pre-revision data Intervening years by interpolation with pre-revision (or revised) growth rates

The 2001 time series revision Conceptual revisions superimposed on pre-revision data year by year (I.2) Statistical revisions interpolated between benchmark years (II.2) Balancing of the results, year by year from 2000 back to 1969/1980 Strict process, good quality results, but (again) required much time and resources…..

Requirements for future time series revisions Harmonisation of revision policy within EU Users want revised time series faster Budget reduction

Points of consideration (1) EU regulations: I/O tables back to 2000, main aggregates back to 1980 Main user: detailed >30 yr time series

Points of consideration (2) From scratch or using pre-revision results Working level of detail Compiling the time series in parallel with the revision year

Points of consideration (3) How to avoid (reduce) the need for year-by-year balancing? Automatic balancing methods

Discussion International harmonisation of revision policy for time series? Inventory of methods currently used in different countries