The zero-truncated symmetrical bivariate negative binomial distribution

While dealing with many real life situations usually the frequency of the zeroth cell of a bivariate distribution is either not available or difficult to record. Keeping this fact in view the symmetrical bivariate negative binomial distribution has been modified in this paper, and the modified model has been referred to as the zero-truncated symmetrical bivariate negative binomial distribution. Apart from fitting the model to an observed and reported bivariate data set, some new results are given which may help in understanding the chance mechanisms that generate the bivariate distribution.