I've been told it is reasonable to add the averages of several groups to get the "total mean" (for lack of a better word) of the groups. For example you could add the average abundance of several species of fish to get a total abundance value for allspecies. I have three questions about this procedure:
1) Does it make sense and if so could someone explain in words what it means and how it is used?
2) Is there a term for this value?
3) I found a procedure on a web page for calculating the standard deviation (not additive) of this value but this raised a new question - how does it make sense to have a standard deviation for a total?
4) If it makes sense so far, is there a way to calculate standard error for this value?
5) If this value is not a mean, can it be used in statistical tests?
Thanks for any help.
On Tuesday, July 28, 2009 at 5:08:21 PM UTC-7, Walt987 wrote:species. I have three questions about this procedure:
I've been told it is reasonable to add the averages of several groups to get the "total mean" (for lack of a better word) of the groups. For example you could add the average abundance of several species of fish to get a total abundance value for all
the case where you can add averages.)
1) Does it make sense and if so could someone explain in words what it means and how it is used?
2) Is there a term for this value?
3) I found a procedure on a web page for calculating the standard deviation (not additive) of this value but this raised a new question - how does it make sense to have a standard deviation for a total?
4) If it makes sense so far, is there a way to calculate standard error for this value?
5) If this value is not a mean, can it be used in statistical tests?
Thanks for any help.
If you own a store and the average cost of the shoes you buy to stock your store is $50 and the average cost of the clothes you buy for your store is $46 then the total average cost of the clothes AND shoes you buy for the store is $50+$46=$96. (This is
You cannot add averages if for example your one class got an average of 50% on their test and you have another class that got 75% on their test, you can't add their averages and say the combined average for your two classes is 50% +75%=125%. (It doesn'tmake sense to add averages in this case)
Let me know what you think...
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