Formula for the cross covariance of sums of random vectors?












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Is there a general formula for the cross covariance for sums of random vectors?



Let $A = sum_{i=1}^nc_iX_i$ where each $X_i$ is an $n$-dimensional random vector.



Let $B = sum_{j=1}^n b_jY_j$ be defined similarly.



Is there a formula for $text{Cov}(A,B)$?



And for the special case assuming that each $X_i,Y_i$ has mean and covariance $mu$ and $Sigma$, respectively. What does this reduce to?



I'm assuming it's something of the form:



$sum_{i=1}^nsum_{j=1}^n c_ib_itext{Cov($X_i, Y_i$)}$, but I'm not entirely sure.










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    0












    $begingroup$


    Is there a general formula for the cross covariance for sums of random vectors?



    Let $A = sum_{i=1}^nc_iX_i$ where each $X_i$ is an $n$-dimensional random vector.



    Let $B = sum_{j=1}^n b_jY_j$ be defined similarly.



    Is there a formula for $text{Cov}(A,B)$?



    And for the special case assuming that each $X_i,Y_i$ has mean and covariance $mu$ and $Sigma$, respectively. What does this reduce to?



    I'm assuming it's something of the form:



    $sum_{i=1}^nsum_{j=1}^n c_ib_itext{Cov($X_i, Y_i$)}$, but I'm not entirely sure.










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      Is there a general formula for the cross covariance for sums of random vectors?



      Let $A = sum_{i=1}^nc_iX_i$ where each $X_i$ is an $n$-dimensional random vector.



      Let $B = sum_{j=1}^n b_jY_j$ be defined similarly.



      Is there a formula for $text{Cov}(A,B)$?



      And for the special case assuming that each $X_i,Y_i$ has mean and covariance $mu$ and $Sigma$, respectively. What does this reduce to?



      I'm assuming it's something of the form:



      $sum_{i=1}^nsum_{j=1}^n c_ib_itext{Cov($X_i, Y_i$)}$, but I'm not entirely sure.










      share|cite|improve this question









      $endgroup$




      Is there a general formula for the cross covariance for sums of random vectors?



      Let $A = sum_{i=1}^nc_iX_i$ where each $X_i$ is an $n$-dimensional random vector.



      Let $B = sum_{j=1}^n b_jY_j$ be defined similarly.



      Is there a formula for $text{Cov}(A,B)$?



      And for the special case assuming that each $X_i,Y_i$ has mean and covariance $mu$ and $Sigma$, respectively. What does this reduce to?



      I'm assuming it's something of the form:



      $sum_{i=1}^nsum_{j=1}^n c_ib_itext{Cov($X_i, Y_i$)}$, but I'm not entirely sure.







      linear-algebra statistics definition






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      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 28 at 19:19









      Oliver GOliver G

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