In: Statistics and Probability
Let 𝑋1, 𝑋2,…, 𝑋𝑛 be a random sample of a gamma distribution with parameters 𝛼 (known) and 𝛽 (unknown), prove that 𝑇 (𝑿) = 𝑋̅ is a sufficient estimator for 𝛽.
Let
be a random sample from the pdf or pmf
. Then the statistics
is sufficient for
, iff we can factorize the joint PDF and PMF of
as
Where
depends on
but not on
and
depends on
and on
only through
In our problem
with pdf :
Join density function is given by:
Now let,
Cleraly
depends on
but not on
But
depends depends on
and on
only through
Hence factorization theorem implies is sufficient Statistics for estimator