Hello, everyone;

I have a mixed probability function:

q+(1-q)*NB(0,r,p) for k=0;

(1-q)*NB(k,r,p) for k>0;

NB(k,r,p)=Gamma(k+r)/(Gamma(r)*(Gamma(k+1))*p^k*(1-p)^r

How can I calculate the Mean and Variance of this mixed function?

Thanks!

Maryann(Nod)