**Tweedle Notes**

used as distribution for GLMs
with cluster at x=0
use case: any industry with mix(zeros, non-negative continuous data)
features: mean, variance = mu * mean^p
mu = dispersion, p = index parameter
not defined for p=0->1, Y>0
continuous for p=1->2, with mass at y=0
continuous for p>2, for Y>0
p=1 --> Poisson; p=2 --> gamma, p=3 --> invGaussian