Mean and standard deviation on the HP25
12-01-2017, 06:16 PM (This post was last modified: 12-01-2017 06:22 PM by Dieter.)
Post: #1
 Dieter Senior Member Posts: 2,397 Joined: Dec 2013
Mean and standard deviation on the HP25
Hi all,

I would like to ask the HP25 owners here to do a little test that might show how this calculator behaves different from later devices.

First of all the Σ+ function stores Σx, Σy, Σx², Σxy and n, but not Σy². So the standard deviation of y cannot be calculated, only sx is calculated. This also applies to the mean, only the mean of x is returned.

But... newer calculators return mean and standard deviation for both X and Y, and they overwrite the respective stack registers. If the stack is filled with 1, 2, 3 and 4, this is what an HP67 or HP41 returns:

Code:
mean: T 1      1 Z 2  =>  2 Y 3      y-mean X 4      x-mean standard deviation: T 1      1 Z 2  =>  2 Y 3      y-sdev X 4      x-sdev

This seems to be different on the HP25:

Code:
mean: T 1      2 Z 2  =>  3 Y 3      4 X 4      x-mean standard deviation: T 1      2 Z 2  =>  3 Y 3      4 X 4      x-sdev

So the HP25 does not seem to overwrite X, instead it calculates the respective value and pushes the stack.

Could the HP25 owners here please try and confirm this?
Or correct me if I'm wrong, of course. ;-)

Dieter
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 Messages In This Thread Mean and standard deviation on the HP25 - Dieter - 12-01-2017 06:16 PM RE: Mean and standard deviation on the HP25 - PANAMATIK - 12-01-2017, 06:35 PM RE: Mean and standard deviation on the HP25 - Dieter - 12-03-2017, 04:49 PM

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