Contents
When to use Poisson distribution and gamma distribution?
Poisson distribution is used to model the # of events in the future, Exponential distribution is used to predict the wait time until the very first event, and Gamma distribution is used to predict the wait time until the k-th event.
Which is the correct order to read gamma distributions?
Understanding them well is absolutely required for understanding the Gamma well. The order of your reading should be 1. Poisson, 2. Exponential, 3. Gamma.
Why are there two different parameterization sets for gamma?
There are two aspects of Gamma’s parameterization that confuse us! One is that it has two different parameterization sets — ( k, θ) & ( α, β) — and different forms of PDF. The other is that there is no universal consensus of what the “ scale ” parameter should be.
What’s the difference between gamma distribution and exponential distribution?
Then, what’s the difference between exponential distribution and gamma distribution? The exponential distribution predicts the wait time until the *very first* event. The gamma distribution, on the other hand, predicts the wait time until the *k-th* event occurs. 2.
Is the gamma distribution a shape or a scale?
Parameters of Gamma: a shape or a scale?! There are two aspects of Gamma’s parameterization that confuse us! One is that it has two different parameterization sets — ( k, θ) & ( α, β) — and different forms of PDF. The other is that there is no universal consensus of what the “ scale ” parameter should be.
Is the PDF format the same as the parametrization?
The PDF stays the same format as what we’ve derived. For (k, θ) parameterization: θ is a reciprocal of the event rate λ, which is the mean wait time (the average time between event arrivals). Even though the PDFs have different formats, both parametrizations generate the same model.