So the negative binomial distribution isreally like binomial distribution.
Binomial distribution: the percentage of reaching certain times of success in the fixed times of trial.
Negative binomial distribution: the number of trials needed to get a certain times of success.
So if you want to get a third success in the 10th time, and the success rate is 0.03, the failure rate is 0.97, then you have to have 2 times of success in 9 times.
Then get the last success in the 10th time.
Get it!!!
