Let $Y:= -2displaystylesum_{i=1}^n ln F_{X_i}(X_i)$. Prove that $Y$ have distribution $chi^2(2n)$












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If $X_1,X_2,ldots,X_n$ be independent random variables each with distribution function $F_{X_i}$. Let $$Y:= -2sum_{i=1}^n ln F_{X_i}(X_i).$$



Prove that $Y$ have distribution $chi^2(2n)$.



I'm trying solve this problem, but I can't. Any hints or tip? Thanks for your help.










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  • Meeow - my mistake.
    – wolfies
    Oct 17 '13 at 11:53
















0














If $X_1,X_2,ldots,X_n$ be independent random variables each with distribution function $F_{X_i}$. Let $$Y:= -2sum_{i=1}^n ln F_{X_i}(X_i).$$



Prove that $Y$ have distribution $chi^2(2n)$.



I'm trying solve this problem, but I can't. Any hints or tip? Thanks for your help.










share|cite|improve this question
























  • Meeow - my mistake.
    – wolfies
    Oct 17 '13 at 11:53














0












0








0







If $X_1,X_2,ldots,X_n$ be independent random variables each with distribution function $F_{X_i}$. Let $$Y:= -2sum_{i=1}^n ln F_{X_i}(X_i).$$



Prove that $Y$ have distribution $chi^2(2n)$.



I'm trying solve this problem, but I can't. Any hints or tip? Thanks for your help.










share|cite|improve this question















If $X_1,X_2,ldots,X_n$ be independent random variables each with distribution function $F_{X_i}$. Let $$Y:= -2sum_{i=1}^n ln F_{X_i}(X_i).$$



Prove that $Y$ have distribution $chi^2(2n)$.



I'm trying solve this problem, but I can't. Any hints or tip? Thanks for your help.







probability statistics






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edited Oct 17 '13 at 11:34









Stefan Hansen

20.7k73663




20.7k73663










asked Oct 17 '13 at 0:32









user63192

614411




614411












  • Meeow - my mistake.
    – wolfies
    Oct 17 '13 at 11:53


















  • Meeow - my mistake.
    – wolfies
    Oct 17 '13 at 11:53
















Meeow - my mistake.
– wolfies
Oct 17 '13 at 11:53




Meeow - my mistake.
– wolfies
Oct 17 '13 at 11:53










1 Answer
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Hints:




  1. Show that $F_X(X)$ is uniformly distributed in $(0,1)$ for any random variable $X$ with distribution function $F_X$.


  2. Show that $-2log(U)$ follows a $chi^2(2)$ distribution if $U$ is uniformly distributed in $(0,1)$. Note that a $chi^2(2)$ distribution is the same as an exponential distribution with parameter $tfrac12$.


  3. Conclude using that $X+Ysimchi^2(n_1+n_2)$ if $Xsim chi^2(n_1)$ and $Ysimchi^2(n_2)$ are independent (this property is most easily shown using characteristic functions).







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    1 Answer
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    Hints:




    1. Show that $F_X(X)$ is uniformly distributed in $(0,1)$ for any random variable $X$ with distribution function $F_X$.


    2. Show that $-2log(U)$ follows a $chi^2(2)$ distribution if $U$ is uniformly distributed in $(0,1)$. Note that a $chi^2(2)$ distribution is the same as an exponential distribution with parameter $tfrac12$.


    3. Conclude using that $X+Ysimchi^2(n_1+n_2)$ if $Xsim chi^2(n_1)$ and $Ysimchi^2(n_2)$ are independent (this property is most easily shown using characteristic functions).







    share|cite|improve this answer


























      1














      Hints:




      1. Show that $F_X(X)$ is uniformly distributed in $(0,1)$ for any random variable $X$ with distribution function $F_X$.


      2. Show that $-2log(U)$ follows a $chi^2(2)$ distribution if $U$ is uniformly distributed in $(0,1)$. Note that a $chi^2(2)$ distribution is the same as an exponential distribution with parameter $tfrac12$.


      3. Conclude using that $X+Ysimchi^2(n_1+n_2)$ if $Xsim chi^2(n_1)$ and $Ysimchi^2(n_2)$ are independent (this property is most easily shown using characteristic functions).







      share|cite|improve this answer
























        1












        1








        1






        Hints:




        1. Show that $F_X(X)$ is uniformly distributed in $(0,1)$ for any random variable $X$ with distribution function $F_X$.


        2. Show that $-2log(U)$ follows a $chi^2(2)$ distribution if $U$ is uniformly distributed in $(0,1)$. Note that a $chi^2(2)$ distribution is the same as an exponential distribution with parameter $tfrac12$.


        3. Conclude using that $X+Ysimchi^2(n_1+n_2)$ if $Xsim chi^2(n_1)$ and $Ysimchi^2(n_2)$ are independent (this property is most easily shown using characteristic functions).







        share|cite|improve this answer












        Hints:




        1. Show that $F_X(X)$ is uniformly distributed in $(0,1)$ for any random variable $X$ with distribution function $F_X$.


        2. Show that $-2log(U)$ follows a $chi^2(2)$ distribution if $U$ is uniformly distributed in $(0,1)$. Note that a $chi^2(2)$ distribution is the same as an exponential distribution with parameter $tfrac12$.


        3. Conclude using that $X+Ysimchi^2(n_1+n_2)$ if $Xsim chi^2(n_1)$ and $Ysimchi^2(n_2)$ are independent (this property is most easily shown using characteristic functions).








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        share|cite|improve this answer










        answered Oct 17 '13 at 11:32









        Stefan Hansen

        20.7k73663




        20.7k73663






























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