HISTORICAL COMPARISONS OF INCOME:

The expansion of quantitative economic history has increased the need for new data at national and international levels. Efforts to produce new historical national accounts are now widespread in Europe rendering data sets widely used in the past (i.e., Bairoch 1976) obsolete. In turn, a shift towards a macro-economic approach in the narrative of European history has taken place that outdates classical textbooks written in a sectoral, industry by industry fashion, and makes the prospects for a new, comparative history of Europe look brighter than it seemed to a decade ago (O'Brien 1986). Historical comparisons of product per head across countries usually start from present day levels of GDP, adjusted for its purchasing power (PPP), extrapolated backwards with growth rates taken from national accounts.2 It is the aim of this paper to contribute to the debate on comparative perfor-mance through a more economically sound alternative. By providing PPP adjusted levels of output at current prices, the new approach improves GDP cross-sectional comparability, as it represents a superior alternative to usual constant price comparisons. CROSS-COUNTRY COMPARISONS OVER TIME Substituting purchasing power parity adjusted exchange rates for trading exchange rates has become common practice in international GDP compa-risons with pervasive effects on country rankings. Historical comparisons have been affected by the new comparative approach and levels of product per person or per worker for remote years are now expressed in present-tim