<Tr> <Td> </Td> <Td> This section includes a list of references, but its sources remain unclear because it has insufficient inline citations . Please help to improve this section by introducing more precise citations . (March 2011) (Learn how and when to remove this template message) </Td> </Tr> <Ul> <Li> Exponential distribution is closed under scaling by a positive factor . If X ~ Exp (λ) then kX ~ Exp (λ / k). </Li> <Li> If X ~ Exp (1 / 2) then X ∼ χ, i.e. X has a chi - squared distribution with 2 degrees of freedom . Hence: </Li> </Ul> <Li> Exponential distribution is closed under scaling by a positive factor . If X ~ Exp (λ) then kX ~ Exp (λ / k). </Li> <Li> If X ~ Exp (1 / 2) then X ∼ χ, i.e. X has a chi - squared distribution with 2 degrees of freedom . Hence: </Li>

The poisson distribution is a special case of the exponential distribution