Bass model is used to predict new product adoption using sales data. It is one of the most widely used model for new product diffusion. It consists of three parameters.
p: innovator parameter
q: imitator parameter
m: potential market size
f(t) represents the change of customer base as a fraction of the total, F(t) shows the customer base as a fraction of the total. When you multiply the f(t) by m, the potential market size, it becomes sales number of units sold at time t.
Sales is denoted as S(t)