classification
Title: Clarify the difference between mu and xbar in the statistics documentation
Type: behavior Stage:
Components: Documentation Versions: Python 3.8
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: cheryl.sabella Nosy List: cheryl.sabella, davin, docs@python, rhettinger, steven.daprano
Priority: normal Keywords:

Created on 2019-02-24 03:39 by steven.daprano, last changed 2019-02-24 11:27 by cheryl.sabella.

Messages (5)
msg336424 - (view) Author: Steven D'Aprano (steven.daprano) * (Python committer) Date: 2019-02-24 03:39
The documentation isn't clear as to the difference between mu and xbar, and why one is used in variance and the other in pvariance.

See #36018 for discussion.

For the record: mu or μ is the population parameter, i.e. the mean of the entire population, if you could average every individual. xbar or x̅  is the mean of a sample.
msg336434 - (view) Author: Davin Potts (davin) * (Python committer) Date: 2019-02-24 05:30
Without necessarily defining what each means, perhaps it is sufficient to change this clause in the docs:
    it should be the mean of data

For pvariance() it could read as:
    it should be the *population* mean of data

And for variance() it could read as:
    it should be the *sample* mean of data
msg336438 - (view) Author: Raymond Hettinger (rhettinger) * (Python committer) Date: 2019-02-24 06:08
> Without necessarily defining what each means, 
> perhaps it is sufficient to change this clause in the docs

+1 That is a simple way to address the concern.
msg336447 - (view) Author: Steven D'Aprano (steven.daprano) * (Python committer) Date: 2019-02-24 08:05
I'm happy with that doc change.

If nobody objects, this might make an easy "Good first issue" for the upcoming sprint. Assigning to Cheryl to stop anyone else grabbing it.
msg336463 - (view) Author: Cheryl Sabella (cheryl.sabella) * (Python committer) Date: 2019-02-24 11:27
Great!  Thank you, Steven.
History
Date User Action Args
2019-02-24 11:27:48cheryl.sabellasetmessages: + msg336463
2019-02-24 08:05:25steven.dapranosetassignee: docs@python -> cheryl.sabella

messages: + msg336447
nosy: + cheryl.sabella
2019-02-24 06:08:30rhettingersetnosy: + rhettinger
messages: + msg336438
2019-02-24 05:30:53davinsetnosy: + davin
messages: + msg336434
2019-02-24 03:39:59steven.dapranocreate