Philip Fisher’s sense of numbers : An account of the use of quantitative reasoning in Philip Fisher’s qualitative model of equity valuation

Purpose – This paper aims to propose an account of the use of numbers and mathematical formulae and, more generally, of the quantitative aspects in the qualitative equity valuation model of the American investor Philip A. Fisher who is considered to be one of the fathers of the qualitative equity valuation models. Design/methodology/approach – A Conceptual analysis was conducted (Glasersfeld, 1992) of the four volumes published by Fisher between 1954 and 1980 (1958, 1960, 1975, 1980) in relation to his equity valuation process. On the basis of this analysis, a modelization of this author’s perspective on quantitative instruments was built. Findings – A modelization to use quantitative data in a qualitative equity valuation model that is sufficiently detailed and useful for an asset manager is proposed. Originality/value – What is propose is a qualitative analysis of quantitative elements in the thought of a qualitative author on the subject of equity valuation. It is believed that this paper could be of interest to all those who use or are involved in the development of qualitative models of equity valuation or business valuation. This work is also an example of how conceptual analysis – generally employed in the field of mathematics education research – can be used to build descriptive models of decision-making processes of individual investors, models designed to enable the reproduction/approximation of the conceptual operations of the investor.