Methods explained.

This article outlines where the perpetual inventory method (PIM) is used within the Office for National Statistics and discusses in detail the key parameters of a PIM; the asset service life, the retirement distribution and the depreciation function. It covers why these parameters are of importance in the application of a PIM and also highlights some of the key related conceptual issues. The article then concludes with an example illustrating how a PIM can be used to estimate gross capital stock, consumption of fixed capital and net capital stock, which are the principal uses of a PIM. [ABSTRACT FROM AUTHOR]