| Abstract: | As an extension to the work of Oliver, the variance-covariance matrices for the powered logistic and Bass equations were obtained and used to show that the addition of a fourth parameter resulted in the estimates for the remaining three parameters corresponding to those of the simple logistic becoming more unreliable. The degree of confidence that could be placed on the estimated parameters of the powered logistic decreased with the degree of asymmetry. However, the Bass equation proved much more resilient to this problem. A Monte Carlo study shows that, in small samples and for data sets that resemble new technologies in the early stages of di usion, the maximum likelihood estimates do not have the desirable properties of estimates based on large samples. |
