how to prove chi-square statistics conforms to chi-square distribution with contingency table?












2














chi-square test(principle used in C4.5's CVP Pruning),



also called chi-square statistics,



also called chi-square goodness-of fit



How to prove



$sum_{i=1}^{i=r}sum_{j=1}^{j=c}frac{(x_{ij}-E_{ij} )^2}{E_{ij}} = chi^2_{(r-1)(c-1)}$



where
$E_{ij}=frac{N_i·N_j}{N}$,



$N$ is the total counts of the whole datasets.



$N_i$ are the counts of the sub-datasets of the same-value of feature



$N_j$ are the counts of the sub-datasets of the same-class



please help,thanks~!



here is contingency table



/------------------------------------------------



here are some references which are not clear:



https://arxiv.org/pdf/1808.09171.pdf (not mention why $k-1$ is used in formula(5))



https://www.math.utah.edu/~davar/ps-pdf-files/Chisquared.pdf (Not mention why $Theta<1$
from (9)->(10))



https://arxiv.org/pdf/1808.09171 (page 4th not mention what is X*with a line on it)



http://personal.psu.edu/drh20/asymp/fall2006/lectures/ANGELchpt07.pdf
(Page 109th,Not mention why $Cov(X_{ij},X_{il}=-p_ip_l)$)










share|cite|improve this question





























    2














    chi-square test(principle used in C4.5's CVP Pruning),



    also called chi-square statistics,



    also called chi-square goodness-of fit



    How to prove



    $sum_{i=1}^{i=r}sum_{j=1}^{j=c}frac{(x_{ij}-E_{ij} )^2}{E_{ij}} = chi^2_{(r-1)(c-1)}$



    where
    $E_{ij}=frac{N_i·N_j}{N}$,



    $N$ is the total counts of the whole datasets.



    $N_i$ are the counts of the sub-datasets of the same-value of feature



    $N_j$ are the counts of the sub-datasets of the same-class



    please help,thanks~!



    here is contingency table



    /------------------------------------------------



    here are some references which are not clear:



    https://arxiv.org/pdf/1808.09171.pdf (not mention why $k-1$ is used in formula(5))



    https://www.math.utah.edu/~davar/ps-pdf-files/Chisquared.pdf (Not mention why $Theta<1$
    from (9)->(10))



    https://arxiv.org/pdf/1808.09171 (page 4th not mention what is X*with a line on it)



    http://personal.psu.edu/drh20/asymp/fall2006/lectures/ANGELchpt07.pdf
    (Page 109th,Not mention why $Cov(X_{ij},X_{il}=-p_ip_l)$)










    share|cite|improve this question



























      2












      2








      2


      2





      chi-square test(principle used in C4.5's CVP Pruning),



      also called chi-square statistics,



      also called chi-square goodness-of fit



      How to prove



      $sum_{i=1}^{i=r}sum_{j=1}^{j=c}frac{(x_{ij}-E_{ij} )^2}{E_{ij}} = chi^2_{(r-1)(c-1)}$



      where
      $E_{ij}=frac{N_i·N_j}{N}$,



      $N$ is the total counts of the whole datasets.



      $N_i$ are the counts of the sub-datasets of the same-value of feature



      $N_j$ are the counts of the sub-datasets of the same-class



      please help,thanks~!



      here is contingency table



      /------------------------------------------------



      here are some references which are not clear:



      https://arxiv.org/pdf/1808.09171.pdf (not mention why $k-1$ is used in formula(5))



      https://www.math.utah.edu/~davar/ps-pdf-files/Chisquared.pdf (Not mention why $Theta<1$
      from (9)->(10))



      https://arxiv.org/pdf/1808.09171 (page 4th not mention what is X*with a line on it)



      http://personal.psu.edu/drh20/asymp/fall2006/lectures/ANGELchpt07.pdf
      (Page 109th,Not mention why $Cov(X_{ij},X_{il}=-p_ip_l)$)










      share|cite|improve this question















      chi-square test(principle used in C4.5's CVP Pruning),



      also called chi-square statistics,



      also called chi-square goodness-of fit



      How to prove



      $sum_{i=1}^{i=r}sum_{j=1}^{j=c}frac{(x_{ij}-E_{ij} )^2}{E_{ij}} = chi^2_{(r-1)(c-1)}$



      where
      $E_{ij}=frac{N_i·N_j}{N}$,



      $N$ is the total counts of the whole datasets.



      $N_i$ are the counts of the sub-datasets of the same-value of feature



      $N_j$ are the counts of the sub-datasets of the same-class



      please help,thanks~!



      here is contingency table



      /------------------------------------------------



      here are some references which are not clear:



      https://arxiv.org/pdf/1808.09171.pdf (not mention why $k-1$ is used in formula(5))



      https://www.math.utah.edu/~davar/ps-pdf-files/Chisquared.pdf (Not mention why $Theta<1$
      from (9)->(10))



      https://arxiv.org/pdf/1808.09171 (page 4th not mention what is X*with a line on it)



      http://personal.psu.edu/drh20/asymp/fall2006/lectures/ANGELchpt07.pdf
      (Page 109th,Not mention why $Cov(X_{ij},X_{il}=-p_ip_l)$)







      probability probability-theory statistics normal-distribution chi-squared






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      edited Nov 26 '18 at 11:44

























      asked Nov 26 '18 at 7:43









      appleyuchi

      113




      113






















          2 Answers
          2






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          0














          The proof uses $x_{ij}approxoperatorname{Poisson}(E_{ij})approx N(E_{ij},,E_{ij})$. The reason for $k-1$ is that $sum_i N_i=N$ removes a degree of freedom. The reason for $Thetale 1$ is because the $theta_i$ are probabilities.






          share|cite|improve this answer





















          • thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
            – appleyuchi
            Nov 26 '18 at 8:05












          • what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
            – appleyuchi
            Nov 26 '18 at 8:25










          • For the Poisson distribution the mean is equal to the variance.
            – Karl
            Nov 26 '18 at 12:32










          • thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
            – appleyuchi
            Nov 27 '18 at 6:52










          • @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
            – J.G.
            Nov 27 '18 at 6:53



















          0














          https://blog.csdn.net/appleyuchi/article/details/84567158



          I try to prove it from multi-nominal distribution.
          The above link is my record,NOT very rigorous,



          If there are something wrong ,please let me know,thanks.



          If there are other proof which is much easier to understand ,please let me know,thanks.



          Many thanks for all your help~!






          share|cite|improve this answer























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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

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            active

            oldest

            votes









            0














            The proof uses $x_{ij}approxoperatorname{Poisson}(E_{ij})approx N(E_{ij},,E_{ij})$. The reason for $k-1$ is that $sum_i N_i=N$ removes a degree of freedom. The reason for $Thetale 1$ is because the $theta_i$ are probabilities.






            share|cite|improve this answer





















            • thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
              – appleyuchi
              Nov 26 '18 at 8:05












            • what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
              – appleyuchi
              Nov 26 '18 at 8:25










            • For the Poisson distribution the mean is equal to the variance.
              – Karl
              Nov 26 '18 at 12:32










            • thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
              – appleyuchi
              Nov 27 '18 at 6:52










            • @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
              – J.G.
              Nov 27 '18 at 6:53
















            0














            The proof uses $x_{ij}approxoperatorname{Poisson}(E_{ij})approx N(E_{ij},,E_{ij})$. The reason for $k-1$ is that $sum_i N_i=N$ removes a degree of freedom. The reason for $Thetale 1$ is because the $theta_i$ are probabilities.






            share|cite|improve this answer





















            • thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
              – appleyuchi
              Nov 26 '18 at 8:05












            • what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
              – appleyuchi
              Nov 26 '18 at 8:25










            • For the Poisson distribution the mean is equal to the variance.
              – Karl
              Nov 26 '18 at 12:32










            • thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
              – appleyuchi
              Nov 27 '18 at 6:52










            • @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
              – J.G.
              Nov 27 '18 at 6:53














            0












            0








            0






            The proof uses $x_{ij}approxoperatorname{Poisson}(E_{ij})approx N(E_{ij},,E_{ij})$. The reason for $k-1$ is that $sum_i N_i=N$ removes a degree of freedom. The reason for $Thetale 1$ is because the $theta_i$ are probabilities.






            share|cite|improve this answer












            The proof uses $x_{ij}approxoperatorname{Poisson}(E_{ij})approx N(E_{ij},,E_{ij})$. The reason for $k-1$ is that $sum_i N_i=N$ removes a degree of freedom. The reason for $Thetale 1$ is because the $theta_i$ are probabilities.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Nov 26 '18 at 7:52









            J.G.

            23k22137




            23k22137












            • thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
              – appleyuchi
              Nov 26 '18 at 8:05












            • what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
              – appleyuchi
              Nov 26 '18 at 8:25










            • For the Poisson distribution the mean is equal to the variance.
              – Karl
              Nov 26 '18 at 12:32










            • thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
              – appleyuchi
              Nov 27 '18 at 6:52










            • @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
              – J.G.
              Nov 27 '18 at 6:53


















            • thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
              – appleyuchi
              Nov 26 '18 at 8:05












            • what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
              – appleyuchi
              Nov 26 '18 at 8:25










            • For the Poisson distribution the mean is equal to the variance.
              – Karl
              Nov 26 '18 at 12:32










            • thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
              – appleyuchi
              Nov 27 '18 at 6:52










            • @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
              – J.G.
              Nov 27 '18 at 6:53
















            thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
            – appleyuchi
            Nov 26 '18 at 8:05






            thanks for your replies,could you please give a proof with details about the xij≈Poisson(Eij)≈N(Eij,Eij)?THANKS.
            – appleyuchi
            Nov 26 '18 at 8:05














            what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
            – appleyuchi
            Nov 26 '18 at 8:25




            what's the meaning of xij≈Poisson(Eij)≈N(Eij,Eij)?
            – appleyuchi
            Nov 26 '18 at 8:25












            For the Poisson distribution the mean is equal to the variance.
            – Karl
            Nov 26 '18 at 12:32




            For the Poisson distribution the mean is equal to the variance.
            – Karl
            Nov 26 '18 at 12:32












            thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
            – appleyuchi
            Nov 27 '18 at 6:52




            thanks for your replies,but what's the meaning of "xij≈Poisson(Eij)"?
            – appleyuchi
            Nov 27 '18 at 6:52












            @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
            – J.G.
            Nov 27 '18 at 6:53




            @appleyuchi That $x_{ij}$ is approximately Poisson-distributed.
            – J.G.
            Nov 27 '18 at 6:53











            0














            https://blog.csdn.net/appleyuchi/article/details/84567158



            I try to prove it from multi-nominal distribution.
            The above link is my record,NOT very rigorous,



            If there are something wrong ,please let me know,thanks.



            If there are other proof which is much easier to understand ,please let me know,thanks.



            Many thanks for all your help~!






            share|cite|improve this answer




























              0














              https://blog.csdn.net/appleyuchi/article/details/84567158



              I try to prove it from multi-nominal distribution.
              The above link is my record,NOT very rigorous,



              If there are something wrong ,please let me know,thanks.



              If there are other proof which is much easier to understand ,please let me know,thanks.



              Many thanks for all your help~!






              share|cite|improve this answer


























                0












                0








                0






                https://blog.csdn.net/appleyuchi/article/details/84567158



                I try to prove it from multi-nominal distribution.
                The above link is my record,NOT very rigorous,



                If there are something wrong ,please let me know,thanks.



                If there are other proof which is much easier to understand ,please let me know,thanks.



                Many thanks for all your help~!






                share|cite|improve this answer














                https://blog.csdn.net/appleyuchi/article/details/84567158



                I try to prove it from multi-nominal distribution.
                The above link is my record,NOT very rigorous,



                If there are something wrong ,please let me know,thanks.



                If there are other proof which is much easier to understand ,please let me know,thanks.



                Many thanks for all your help~!







                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Nov 27 '18 at 11:12

























                answered Nov 27 '18 at 7:51









                appleyuchi

                113




                113






























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