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# Calculate skewing data in a XY scatter plot

This probably isn't the right group for this kind of question but I figured
I would take a shot...

I want to remove points that skew a scatter plot. For example 20 data points
are around -75 to 100 on the Y axis but a couple of points are at 1500 and a
couple at -500

How would I figure which points should be removed? Of course I want to
remove the 1500's and -500's.

Nov 17 '05 #1
3 3275
Joe wrote:
How would I figure which points should be removed? Of course I want to
remove the 1500's and -500's.

You could try to calculate the mean value and standard deviation of all
points and remove points that are outside of mean +/- deviation. Repeat
these steps until you are pleased with the result.

hth,
Max, not really a mathematician :o)

Nov 17 '05 #2
Thanks.

Could you possibly provide me with an example? I don't know how to get the
standard deviation.
My math skills are limited to 1 + 2 = 4 ;)

Thanks again.

"Markus Stoeger" <sp******@gmx.at> wrote in message
news:ur**************@TK2MSFTNGP14.phx.gbl...
Joe wrote:
How would I figure which points should be removed? Of course I want to
remove the 1500's and -500's.

You could try to calculate the mean value and standard deviation of all
points and remove points that are outside of mean +/- deviation. Repeat
these steps until you are pleased with the result.

hth,
Max, not really a mathematician :o)

Nov 17 '05 #3
Joe wrote:
Thanks.

Could you possibly provide me with an example? I don't know how to get the
standard deviation.
My math skills are limited to 1 + 2 = 4 ;)

There is a good explanation on
http://en.wikipedia.org/wiki/Standard_deviation
Just scroll down to the example and skip the rest.

I'm not sure how welcome such a discussion is in a c# newsgroup. It would
better fit into a math group. You can also mail me privately if you need
more help on it.

Max

Nov 17 '05 #4

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