It is known that F(t)=1– S(t). Since the data were discreet, the
random variable T was never observed exactly, due to the presence
of censure. Discreet statistical distributions (Weibull, Lognormal,
Gama, exponential) were fitted to the data obtained in the con-
sumer test and the best fit (obtained by a visual inspection of the
curves) used to express F(T) (Fig. 1). For example, if a Weibull
distribution is chosen for T, the rejection function is given by: