This essay is a selective guide to the literature on weak instruments. We use simple models to illustrate the problems raised by weak instruments and the suggestions that have been made to solve them. Because the literature is one that is still developing we only briefly touch on some recent...

Weak instruments have become an issue in many contexts in which econometric methods have been used. Some progress has been made into how one diagnoses the problem and how one makes an allowance for it. The present paper gives a partial survey of this literature, focussing upon some of the major...

We describe different ways of measuring the business cycle. Insti- tutions such as the NBER, OECD and IMF do this through locating the turning points in series taken to represent the aggregate level of economic activity. The turning points are determined according to rules that either come from...

The paper discusses a number of trends in the use of macro-economic models for acquiring information about the macro-economy. It is argued that a fundamental distinction should be drawn between models that are constructed to summarise the data and those which are used to interpret the data. By...