Professional investors using the services of managers of financial assets distinguish different types of analysis when considering whether to entrust them with capital. They commonly oppose a “quantitative analysis” and a “qualitative analysis”. They present them as two partly overlapping knowledge regimes, the addition of which makes it possible to achieve a higher level of knowledge. Rather, both types of analysis, ‘quantitative’ and ‘qualitative’, have functional relationships with each other. In practice, “quantitative analysis” is a retrospective determination of the quality of a fund, which is based on statistical calculations applied to data from price series, i.e. a “performance history”. ‘Qualitative analysis’ means an investigation of the social conditions of production of past performance, and of the reasons for believing that these conditions are sustainable. If those conditions are still met, then it is reasonable to believe that the form of uncertainty reflected in past performance is replicated, and to base the investment decision on the characterisation of the risk that the analysis of past performance allows.