negativeBinomial

negativeBinomial, function

def pure negativeBinomial(mu: number, dispersion: number): ranvar
def pure negativeBinomial(mu: number, dispersion: number, zeroInflation: number): ranvar

Returns the negative binomial distribution with mean mu and dispersion dispersion. The zeroInflation overload adds extra mass at zero.

• mu: mean of the distribution, must be positive.
• dispersion: variance divided by mean, must be >= 1.
• zeroInflation: extra mass at zero, in [0, 1].

Examples

table T = with
  [| as Mu, as Dispersion |]
  [| 2, 1.5 |]
  [| 5, 2.0 |]

T.R = negativeBinomial(T.Mu, T.Dispersion)

show table "Negative binomial" with
  T.Mu
  T.Dispersion
  mean(T.R) as "Mean"

This produces the following table:

table T = with
  [| as Mu, as Dispersion, as ZeroInflation |]
  [| 2, 1.5, 0.2 |]

T.R = negativeBinomial(T.Mu, T.Dispersion, T.ZeroInflation)

show table "Zero inflated" with
  T.ZeroInflation
  mean(T.R) as "Mean"

This produces the following table:

See also

• negative binomial distribution