Michael J. Stewart is a consultant specialising in econometric analysis of the sales effects of advertising of consumer goods. He read psychology and physics at Liverpool University. After four years in the marketing services department of H.J. Heinz (UK) Ltd, and eight years managing the market analysis unit of Beecham Products Ltd, he set up Abbey management Services in 1981. He has published papers in the Journal of the Market Research Society and Admap, and presented papers to ESOMAR. His special interest is incorporating the, often under-estimated, effects of weather in econometric models.