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Math Help - Please can someone help with Correlation coefficient

  1. #1
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    Question Please can someone help with Correlation coefficient

    Hi

    I am really struggling with finding the correlation coefficient for this set of data:

    1991 947
    1992 1098
    1993 1108
    1994 1107
    1995 1615
    1996 2282
    1997 2766
    1998 2505
    1999 2501
    2000 2637

    I think I know the formula I just dont ever seem to be able to get an answer.

    Thank you
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  2. #2
    MHF Contributor matheagle's Avatar
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    The correlation coefficient is the ratio of the covariance over the standard deviations.
    In this case it would be smart to subtract off a number like 2000 or 1990 from the first column.
    If the first column are x's and the second are y's, you will need...

    \sum x_i and \sum x^2_i and \sum y_i and \sum y^2_i and \sum x_iy_i.
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  3. #3
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    Smile

    Thank you for your help but now i am more confussed is there any way you could please break it down for me

    Thank you



    Quote Originally Posted by matheagle View Post
    The correlation coefficient is the ratio of the covariance over the standard deviations.
    In this case it would be smart to subtract off a number like 2000 or 1990 from the first column.
    If the first column are x's and the second are y's, you will need...

    \sum x_i and \sum x^2_i and \sum y_i and \sum y^2_i and \sum x_iy_i.
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  4. #4
    MHF Contributor matheagle's Avatar
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    Obtain those five sums and I will help you.
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  5. #5
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    x= 19955
    y= 18560
    x2= 3.9820
    y2= 3.9474
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  6. #6
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    Quote Originally Posted by rose View Post
    x= 19955
    y= 18560
    x2= 3.9820
    y2= 3.9474
    There's one more sum you need to calculate. Then substitute the sums into the formula given here: Computing Pearson's Correlation Coefficient
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  7. #7
    MHF Contributor matheagle's Avatar
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    Quote Originally Posted by rose View Post
    x= 19955
    y= 18560
    x2= 3.9820
    y2= 3.9474
    I think you're missing some decimal places on those sums of squares.
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