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Thread: how to calculate SD or SEM of ratios?

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    how to calculate SD or SEM of ratios?




    I have 2 groups of data. Group1: x1,x2,x3,x4. Group2:y1,y2,y3,y4. I want to
    get the ratio of y over x (Y/X) and also needs to know the SD or SEM of the
    ratio. How to calculate the SD or SEM of Y/X? In my data, I can use y1/x1,
    or y1/x2 or y1/x3 or y1/x4. x1 is not only related to y1, but can also
    related y2 or y3 or y4, (what i mean is I can also use y2/x1 or y3/x1 or y4/
    x1)
    Please help.
    Thanks!

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    Re: how to calculate SD or SEM of ratios?

    Not familiar with this, but I am familiar with odds ratios. Never heard of SDs or SEM with ratios, though they may exist. The following is the formula for the standard errors of odds ratio. Also this can be used to calculate 95% confidence intervals.

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    Re: how to calculate SD or SEM of ratios?

    Are X and Y independent?
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    Re: how to calculate SD or SEM of ratios?


    Good question Dason. I believe what Dason is getting at may be if covariance may exist in their relationship.
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