what I'm missing in those formulas, and in the Wikipedia, is a
discussion of the prerequisites - it seems to me that, roughly speaking,
if the standard deviation of B is as large or larger than the absolute
value of the mean of B, then we might divide by 0 when calculating A/B .
This should influence the standard deviation of the calculated A/B, I
think, and seems not to be captured by the formulas cited so far.
best,
Kay
Am 20:59, schrieb James Stroud:
> The short answer can be found in item 2 in this link:
>
> http://science.widener.edu/svb/stats/error.html
>
> The long answer is "I highly recommend Error Analysis by John Taylor:"
>
> http://science.widener.edu/svb/stats/error.html
>
> If you can find the first edition (which can fit in your pocket) then
> consider yourself lucky. Later editions suffer book bloat.
>
> James
>
>
> On Jun 4, 2011, at 10:44 AM, capricy gao wrote:
>
>>
>> If means and standard deviations of A and B are known, how to estimate
>> the variance of A/B?
>>
>> Thanks.
>>
>
--
Kay Diederichs http://strucbio.biologie.uni-konstanz.de
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