The quasi-binomial distribution is a small perturbation of the binomial distribution. The mass

probability function is defined by

P(X = k) = C^k_np(p + k*phi)^(k-1)(1 -p - k*phi)^(n-k);

where k 0 to n; n; p usual parameters and phi elememt of -p/n , (1-p)/n

Of course, we retrieve the binomial

distribution with phi set to 0.