The WIFO Weekly Economic Index (WWWI) is a calculation system for calculating the real economic activity of the Austrian economy on a weekly and monthly basis. In addition to the weekly and monthly GDP indicators, ten sub-aggregates of the output side and eight sub-aggregates of the expenditure side are estimated on the basis of the Quarterly National Accounts. The WWWI is obtained by summing the growth contributions of the sub-indicators on the output side, which are fully mapped, whereas the output side has a residual reflecting the joint contribution of changes in inventories and the trade balance with non-tourism services.

For each weekly sub-indicator, two types of econometric models are estimated: first, temporal disaggregation models for historical decomposition of previously published monthly and quarterly data to weekly frequency, and second, a nowcasting model for forecasting weekly values at the current margin based on the estimated historical weekly GDP sub-aggregates and observed weekly indicators. The latter include cashless transactions, freight transport performance, passenger flight volumes, Google mobility data, persons registered as unemployed, electricity consumption and pollutant emissions from industry, and international weekly indicators of economic activity.

The estimated disaggregation models are formulated as dynamic factor models in a state-space representation and transformed as forecasts of unobserved weekly values of a quarterly or monthly time series by treating them as missing data and estimating them with the Kalman filter.

All models are updated after each release of new Quarterly National Accounts data and thus always remain consistent with the current national accounts. Some models are additionally revised after the release of relevant monthly data, which may also lead to a revision of the WWWI.