How to find a one dimensional sufficient statistic.












0














Please could you help check my approach to finding a one dimensional sufficient statistic.



Here is the problem.



$X_1,...,X_n$ is a random sample with each $X_i$ having the pdf $f(x;theta)=2theta^2x^{-3} $ and $0<thetaleq x<infty$



Approach



$L(theta;x)= prod_{i=1}^n 2theta^2x^{-3}_i $



$L(theta;x)= 2^n theta^{2n}x^{-3n}_i $



$L(theta;x)= [2^n] [theta^{2n}][x^{-3n}_i] $



So by factorisation theorem, $x^{-3n}_i$ is a sufficient statistic.



Is this right?










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  • A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
    – Lee David Chung Lin
    2 days ago






  • 2




    No. $prod x_i^{-3}=(prod x_i)^{-3}$.
    – StubbornAtom
    2 days ago










  • $prod x_i^{-3}$ is not the same as $x^{-3n}$?
    – Maths Barry
    yesterday












  • @MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
    – StubbornAtom
    yesterday
















0














Please could you help check my approach to finding a one dimensional sufficient statistic.



Here is the problem.



$X_1,...,X_n$ is a random sample with each $X_i$ having the pdf $f(x;theta)=2theta^2x^{-3} $ and $0<thetaleq x<infty$



Approach



$L(theta;x)= prod_{i=1}^n 2theta^2x^{-3}_i $



$L(theta;x)= 2^n theta^{2n}x^{-3n}_i $



$L(theta;x)= [2^n] [theta^{2n}][x^{-3n}_i] $



So by factorisation theorem, $x^{-3n}_i$ is a sufficient statistic.



Is this right?










share|cite|improve this question
























  • A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
    – Lee David Chung Lin
    2 days ago






  • 2




    No. $prod x_i^{-3}=(prod x_i)^{-3}$.
    – StubbornAtom
    2 days ago










  • $prod x_i^{-3}$ is not the same as $x^{-3n}$?
    – Maths Barry
    yesterday












  • @MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
    – StubbornAtom
    yesterday














0












0








0







Please could you help check my approach to finding a one dimensional sufficient statistic.



Here is the problem.



$X_1,...,X_n$ is a random sample with each $X_i$ having the pdf $f(x;theta)=2theta^2x^{-3} $ and $0<thetaleq x<infty$



Approach



$L(theta;x)= prod_{i=1}^n 2theta^2x^{-3}_i $



$L(theta;x)= 2^n theta^{2n}x^{-3n}_i $



$L(theta;x)= [2^n] [theta^{2n}][x^{-3n}_i] $



So by factorisation theorem, $x^{-3n}_i$ is a sufficient statistic.



Is this right?










share|cite|improve this question















Please could you help check my approach to finding a one dimensional sufficient statistic.



Here is the problem.



$X_1,...,X_n$ is a random sample with each $X_i$ having the pdf $f(x;theta)=2theta^2x^{-3} $ and $0<thetaleq x<infty$



Approach



$L(theta;x)= prod_{i=1}^n 2theta^2x^{-3}_i $



$L(theta;x)= 2^n theta^{2n}x^{-3n}_i $



$L(theta;x)= [2^n] [theta^{2n}][x^{-3n}_i] $



So by factorisation theorem, $x^{-3n}_i$ is a sufficient statistic.



Is this right?







statistics statistical-inference






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited 2 days ago

























asked 2 days ago









Maths Barry

286




286












  • A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
    – Lee David Chung Lin
    2 days ago






  • 2




    No. $prod x_i^{-3}=(prod x_i)^{-3}$.
    – StubbornAtom
    2 days ago










  • $prod x_i^{-3}$ is not the same as $x^{-3n}$?
    – Maths Barry
    yesterday












  • @MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
    – StubbornAtom
    yesterday


















  • A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
    – Lee David Chung Lin
    2 days ago






  • 2




    No. $prod x_i^{-3}=(prod x_i)^{-3}$.
    – StubbornAtom
    2 days ago










  • $prod x_i^{-3}$ is not the same as $x^{-3n}$?
    – Maths Barry
    yesterday












  • @MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
    – StubbornAtom
    yesterday
















A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
– Lee David Chung Lin
2 days ago




A friendly advice: title is NOT the first sentence of your question. In particular, see the last bullet: the question post should be comprehensible without the title, even though one should make good use of the title to provide extra info.
– Lee David Chung Lin
2 days ago




2




2




No. $prod x_i^{-3}=(prod x_i)^{-3}$.
– StubbornAtom
2 days ago




No. $prod x_i^{-3}=(prod x_i)^{-3}$.
– StubbornAtom
2 days ago












$prod x_i^{-3}$ is not the same as $x^{-3n}$?
– Maths Barry
yesterday






$prod x_i^{-3}$ is not the same as $x^{-3n}$?
– Maths Barry
yesterday














@MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
– StubbornAtom
yesterday




@MathsBarry Your sufficient statistic is $prod_{i=1}^n x_i^{-3}=x_1^{-3}ldots x_n^{-3}$; the $x_i$'s are not constant as you seem to think.
– StubbornAtom
yesterday










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