Multiplying numbers differently: an epidemiology of contagious convolution

Contemporary data flows in science, business, government, and media draw numbers from two kinds of places. In some places, numbers are assembled and assigned through observing, counting, and measuring. In other places, numbers are assembled in a different way. Such places are usually defined mathematically as functions and implemented algorithmically in software. The numbers that come from them are not necessarily assigned to anything in the world as facts, keys, or codes. They are functional numbers. The time-space signature of calculation that results from the convolution of these two different supply chains of numbers has textures and traits that directly affect the unfolding of events. This paper reconstructs a symptomatic crisis event, the 2009 A/H1N1 ‘swine flu’ influenza pandemic, from the standpoint of number flow in and around epidemiological models. In their sometimes drastic reshaping of lived space-times, epidemics generate and attract a plethora of numbers relating to human/non-human populations, human/non-human biology, vectors of infection, patterns of urban mobility, media use, clinical practice, and laboratory tests. Examining some key mathematical functions, data sets, plots, and computer model code, the paper reconstructs how these different kinds of numbers mix or ‘convolve’. It suggests that the convolution of numbers to predict and control epidemics, or to disentangle different aspects of events more generally, might provoke us to think of how numbers multiply in multiple ways.