Mean Percentage Difference

Posted in: , on 18. Dec. 2008 - 18:25

Please could someone confirm the correct formula for calculating MPD.

At the moment we have some debate, my opinion is the first one correct, however i have a bit of a rebellion going on!

MPD=(A1-A2)/Average (A1:A2)

MPD=(A1-A2)/(A1+A2)/2

I am also open to them both being wrong!

Cheers

Jim ■

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zsk240
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Formulas Are The Same

Posted on 24. Dec. 2008 - 03:51

I may be missing something but in the denominator, you have two expressions for the average. Both expressions are the same. In other words, the average of A1 and A2 is the sum divided by 2.

I think both expressions are correct. ■

I Was Being Stupid

Posted on 24. Dec. 2008 - 05:42

Thanks for the reply, the reason why it was coming out wrongly because there was an issue with the brackets.

Therefore MPD = (|a1-a2|)/average(a1,a2) = (|a1-a2|)/((a1+a2)/2)

Problem resolved!!

Very useful tool this one for those trying to compare results from different samples of the same material. ■