Bakker, Gert P. den (1991).The sensitivity of growth estimates to variations in index number formulae and weighting procedures is discussed. The calculations concern the macro-economic variables for the interwar period in the Netherlands. It appears that the use of different formulae and weights yields large differences in growth rates. Comparisons of GDP growth rates among countries are presently obscured by the use of different deflation methods. There exists an urgent need for standardisation of deflation methods at the international level.