Expected value of Bernoulli variable (for Linear regression model)












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Can anybody explain how the following reduction happens:



enter image description here










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    0












    $begingroup$


    Can anybody explain how the following reduction happens:



    enter image description here










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Can anybody explain how the following reduction happens:



      enter image description here










      share|cite|improve this question











      $endgroup$




      Can anybody explain how the following reduction happens:



      enter image description here







      statistics expected-value






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      edited Jan 13 at 22:51







      Amir

















      asked Jan 13 at 22:38









      AmirAmir

      1034




      1034






















          1 Answer
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          $begingroup$

          begin{align}
          mathbb{E} |y - (R*X) w|^2
          &= p |y - X w|^2 + (1-p) |y|^2
          \
          &= p(|y|^2 - 2 y^top X w + |Xw|^2) + (1-p) |y|^2
          \
          &= (|y|^2 - 2 y^top (p X w) + p^2 |Xw|^2) - p^2 |Xw|^2 + p |Xw|^2
          \
          &= |y - pXw|^2 + p(1-p) |Xw|^2.
          end{align}






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
            $endgroup$
            – Amir
            Jan 13 at 23:03










          • $begingroup$
            @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
            $endgroup$
            – angryavian
            Jan 13 at 23:09










          • $begingroup$
            Thanks for your help.
            $endgroup$
            – Amir
            Jan 13 at 23:22











          Your Answer





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          1 Answer
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          1 Answer
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          $begingroup$

          begin{align}
          mathbb{E} |y - (R*X) w|^2
          &= p |y - X w|^2 + (1-p) |y|^2
          \
          &= p(|y|^2 - 2 y^top X w + |Xw|^2) + (1-p) |y|^2
          \
          &= (|y|^2 - 2 y^top (p X w) + p^2 |Xw|^2) - p^2 |Xw|^2 + p |Xw|^2
          \
          &= |y - pXw|^2 + p(1-p) |Xw|^2.
          end{align}






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
            $endgroup$
            – Amir
            Jan 13 at 23:03










          • $begingroup$
            @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
            $endgroup$
            – angryavian
            Jan 13 at 23:09










          • $begingroup$
            Thanks for your help.
            $endgroup$
            – Amir
            Jan 13 at 23:22
















          2












          $begingroup$

          begin{align}
          mathbb{E} |y - (R*X) w|^2
          &= p |y - X w|^2 + (1-p) |y|^2
          \
          &= p(|y|^2 - 2 y^top X w + |Xw|^2) + (1-p) |y|^2
          \
          &= (|y|^2 - 2 y^top (p X w) + p^2 |Xw|^2) - p^2 |Xw|^2 + p |Xw|^2
          \
          &= |y - pXw|^2 + p(1-p) |Xw|^2.
          end{align}






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
            $endgroup$
            – Amir
            Jan 13 at 23:03










          • $begingroup$
            @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
            $endgroup$
            – angryavian
            Jan 13 at 23:09










          • $begingroup$
            Thanks for your help.
            $endgroup$
            – Amir
            Jan 13 at 23:22














          2












          2








          2





          $begingroup$

          begin{align}
          mathbb{E} |y - (R*X) w|^2
          &= p |y - X w|^2 + (1-p) |y|^2
          \
          &= p(|y|^2 - 2 y^top X w + |Xw|^2) + (1-p) |y|^2
          \
          &= (|y|^2 - 2 y^top (p X w) + p^2 |Xw|^2) - p^2 |Xw|^2 + p |Xw|^2
          \
          &= |y - pXw|^2 + p(1-p) |Xw|^2.
          end{align}






          share|cite|improve this answer









          $endgroup$



          begin{align}
          mathbb{E} |y - (R*X) w|^2
          &= p |y - X w|^2 + (1-p) |y|^2
          \
          &= p(|y|^2 - 2 y^top X w + |Xw|^2) + (1-p) |y|^2
          \
          &= (|y|^2 - 2 y^top (p X w) + p^2 |Xw|^2) - p^2 |Xw|^2 + p |Xw|^2
          \
          &= |y - pXw|^2 + p(1-p) |Xw|^2.
          end{align}







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 13 at 22:43









          angryavianangryavian

          41.1k23380




          41.1k23380












          • $begingroup$
            Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
            $endgroup$
            – Amir
            Jan 13 at 23:03










          • $begingroup$
            @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
            $endgroup$
            – angryavian
            Jan 13 at 23:09










          • $begingroup$
            Thanks for your help.
            $endgroup$
            – Amir
            Jan 13 at 23:22


















          • $begingroup$
            Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
            $endgroup$
            – Amir
            Jan 13 at 23:03










          • $begingroup$
            @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
            $endgroup$
            – angryavian
            Jan 13 at 23:09










          • $begingroup$
            Thanks for your help.
            $endgroup$
            – Amir
            Jan 13 at 23:22
















          $begingroup$
          Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
          $endgroup$
          – Amir
          Jan 13 at 23:03




          $begingroup$
          Thank you so much, it was very helpful. Would you please give me a clue what is happened in the first line? Is it Bernoulli property?
          $endgroup$
          – Amir
          Jan 13 at 23:03












          $begingroup$
          @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
          $endgroup$
          – angryavian
          Jan 13 at 23:09




          $begingroup$
          @Amir I used the law of total expectation with the two cases $R=0$ and $R=1$.
          $endgroup$
          – angryavian
          Jan 13 at 23:09












          $begingroup$
          Thanks for your help.
          $endgroup$
          – Amir
          Jan 13 at 23:22




          $begingroup$
          Thanks for your help.
          $endgroup$
          – Amir
          Jan 13 at 23:22


















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