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Let's say I'm reading a paper, and the authors write $\alpha \sim \text{gamma}(a, b)$. How do I know which parameterization of the gamma distribution they are using? Is there a convention or must one try to infer from context?

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    $\begingroup$ if they never write it down explicitly, then I you have to infer itfrom context. But if they have a special case where they say: "In the case of the gamma parameters being such and such, we obtain an exponentially distributed rv with whatever", then it's not so bad. $\endgroup$ – mlofton Mar 26 '20 at 18:16
  • $\begingroup$ The mean is the product of those under one parameterisation and their ratio otherwise. You should see information on the mean stated or implied somewhere. $\endgroup$ – Nick Cox Mar 26 '20 at 18:28
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Partially answered in comments:

There might be some conventions, but they would vary between fields ... otherwise:

if they never write it down explicitly, then I you have to infer it from context. But if they have a special case where they say: "In the case of the gamma parameters being such and such, we obtain an exponentially distributed rv with whatever", then it's not so bad.

– mlofton

(and also for the gamma)

The mean is the product of those under one parameterisation and their ratio otherwise. You should see information on the mean stated or implied somewhere.

– Nick Cox

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You may be able to tell from the dimension of the second parameter whether it is a scale or a rate.

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