When he entered advertising in the 60s, none of these questions had satisfactory answers. Many doubted they could ever be answered. Simon did more than anyone to show that advertising can contribute to profit, and that it is not a cost that can be cut with no effect on sales.
He answered advertising questions with the rigour of a mathematician and the clarity of a poet. He read engineering at Cambridge, took an applauded first in mathematics and a diploma in statistics at Magdalen, Oxford, and completed his doctorate in statistics at Imperial, London. His poetry was published by Blackwell's while he was still an undergraduate.
He was among the first to apply the techniques of econometric modelling to sales data. The challenge was to isolate advertising's effects on sales from "noise
in the data caused by changes in factors such as price and distribution. This had been thought to be impossible, but he showed how it could be done.
However, early models showed that advertising's immediate effects on short-term sales are generally small and uneconomic. The value of advertising lies in its long-term effects. He invented concepts such as "adstock
to measure the rate at which advertising decays. The quest he pursued to the end of his life was how to quantify the really long-term effects of advertising on brand strength. His last paper, which will be delivered at the Advertising Research Foundation's conference in New York this month, describes experiments with powerful new models that demonstrate advertising's influence on the underlying sales trend, the "base constant".
The techniques he invented have become the common currency for agencies, clients and analysts around the world. He worked tirelessly to spell out to practitioners the practical applications of his work for budget and media setting. He published more than 200 papers in professional and trade publications, and his books, including Spending Advertising Money, The Advertising Budget, When to Advertise and Accountable Advertising, have become the standard works in their fields.
In 1980, concerned that virtually nothing was publicly available about the economic value of advertising, he created the Advertising Effectiveness Awards for the IPA. Since then, hundreds of account planners, media planners and account handlers have written long, factual essays for the competition, in which entrants are invited to describe the creation and evaluation of a campaign and its contribution to business success. The best papers are published in full in the 11 volumes of Advertising Works.
He had created not only a massive body of evidence that advertising can be a serious business proposition, but also an army of advertising practitioners with first-hand experience of doing evaluations. The UK has become the global centre of excellence for advertising evaluation and the IPA Effectiveness Awards have been copied in many countries.
His lifelong interest was applying statistics to problems that nobody had thought amenable to statistical analysis. His paper to the Royal Statistical Society, In Search of the Ley Hunter, debunked claims for the existence of megalithic ley lines, pointing out that there were fewer alleged lines than would be expected from a random distribution of points between which lines could be drawn. Preparing the paper also allowed him to crawl about in Greenwich Park, testing the likely accuracy of stone-age surveying devices using instruments he had built himself.
Simon's obvious intelligence and integrity could seem intimidating. He did not suffer fools gladly. But he was a man of great charm and generosity, and never let professional disagreements spill over into personal relationships.
To see him rocking with helpless laughter over a glass of champagne at the Garrick, or sitting on the floor with his grandchildren, helping them colour paper aeroplanes, was to understand how he was loved as much as he was respected.
After ten years in industry, he joined Leo Burnett where he worked for the rest of his life. He was the media director, the research and the planning director and vice-chairman of the London office. He spent several years at Burnett's head office in Chicago, where he was the director of brand economics and the vice-president. He founded The Brand Consultancy, a joint venture between Burnett and Arthur Andersen, and BrandCon Ltd, both brand consultancies.
Simon Broadbent died peacefully on 19 March 2002, aged 74, after a short illness, with his four children beside him. He had been working to the end.
At his express request there will not be a memorial service. However, Burnett will be holding a party to celebrate his life and sense of fun - misquoting Byron, he asked: "I pray you remember me, not in your prayers but in your smiles and in your wine."