We show that a conditional average (based on a limit in which the Fourier modes of the turbulent velocity field with wavenumber k⩽kC, where kC is an arbitrary cutoff wavenumber, are held constant) can be used to separate the nonlinear coupling to high-k modes into coherent and random parts,...

This article presents new evidence on the ability of Peacock and Wiseman's displacement hypothesis to explain temporal increases in the ratio of government expenditure to Gross Domestic Product (GDP) in the UK. Using univariate modelling techniques that are robust to structural changes in the...