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Stata and non-numerical correlations   Message List  
Reply | Forward Message #3884 of 4101 |
Re: [Statisticians_group] Stata and non-numerical correlations

Dear Scott R Millis

I hope Christian Schuster (who originated this discussion) may give more information about data. What I could understand is he want to calculate Pearson's 'r'  between two variable amount (range 1-100) and ordinal variable size (small, mid, large mega).

As I suggested in earlier reply that one can calculate canonical correlation by breaking ordinal data in dichotomous variables for getting analogous to Pearson’s r. But it requires a lot of assumptions.

Unfortunately I have not access of book mentioned by you. I will appreciate if you can provide web links for said ideas.

With regards

Nand Kishore


--- On Tue, 27/10/09, SR Millis <srmillis@...> wrote:

From: SR Millis <srmillis@...>
Subject: Re: [Statisticians_group] Stata and non-numerical correlations
To: Statisticians_group@...
Date: Tuesday, 27 October, 2009, 12:25 AM

 

This book does an excellent job of discussing this topic:
 
Chen, P., & Popovich, P. (2002). Correlation: Parametric and nonparametric measures. Thousand Oaks, CA: Sage Publications.
 
Without knowing more about your data/study, it is difficult for me to give precise advice, but you should be able to get this variant of Pearson's r for correlating a continuous variable with an ordinal one by simply running Stata's Pearson r correlation routine on your data.
 
SR Millis

--- On Mon, 10/26/09, Nand Kishore Singh <nk_singh1@yahoo. com> wrote:

From: Nand Kishore Singh <nk_singh1@yahoo. com>
Subject: Re: [Statisticians_ group] Stata and non-numerical correlations
To: Statisticians_ group@yahoogroup s.co.in
Date: Monday, October 26, 2009, 2:38 PM

 
Dear Scott R Millis
Can you elaborate method of calculating Pearson's 'r' between continuous and ordinal variables without any manipulation of data? What is r(RI)? Whether result will be influenced by spacing between numbers used for representing the order?
With regards
Nand Kishore

--- On Sat, 24/10/09, SR Millis <srmillis@yahoo. com> wrote:

From: SR Millis <srmillis@yahoo. com>
Subject: Re: [Statisticians_ group] Stata and non-numerical correlations
To: Statisticians_ group@yahoogroup s.co.in
Date: Saturday, 24 October, 2009, 11:40 PM

 
Correlating a continuous variable with an ordinal variable is simply a special case of Pearson's r: r(RI). Without any manipulation of the data,  r(RI) can be computed using the Pearson's r equation.

SR Millis
~~~~~~~~~~~
"Kunst ist schön, macht aber viel Arbeit."

Scott R Millis, PhD, ABPP (CN,CL,RP), CStat, CSci
Professor & Director of Research
Dept of Physical Medicine & Rehabilitation
Dept of Emergency Medicine
Wayne State University School of Medicine
261 Mack Blvd
Detroit, MI 48201
Email: smillis@med. wayne.edu
Tel: 313-993-8085
Fax: 313-966-7682

--- On Sat, 10/24/09, Christian Schuster <csvirtual@gmx. de> wrote:

From: Christian Schuster <csvirtual@gmx. de>
Subject: [Statisticians_ group] Stata and non-numerical correlations
To: Statisticians_ group@yahoogroup s.co.in
Date: Saturday, October 24, 2009, 1:36 PM

 
Dear members of the group,

I am new to the group and happy to have joined!

Currently I am writing on a thesis and have one issue with Stata where I can't find the right function.
I
want to see if two variables correlate. Both or one of the variables are/is not a numeric variable but a string ( or categorical, or ordinal).
Example:

Variable "size" can have the following content: small, mid, large, mega -> this variable is a string

Variable "amount" can have numbers from 1 to 100 -> numeric variable

Now, I want to see if there is a correlation (for example: "the correlation of a high amount is significant with size "mega" (at a confidence level of...)".
I can't find a function in Stata. It always states that I need a numeric variable with all the functions I tried.

The nptrend (Trend test across ordered groups) comes closest but still you have to have one numeric variable

It would be great if someone could provide me with a quick solution.

Thanks in advance!!

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Wed Oct 28, 2009 2:15 pm

nk_singh1
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Message #3884 of 4101 |
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Dear members of the group, I am new to the group and happy to have joined! Currently I am writing on a thesis and have one issue with Stata where I can't find...
Christian Schuster
csvirtual
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Oct 24, 2009
5:56 pm

Correlating a continuous variable with an ordinal variable is simply a special case of Pearson's r: r(RI). Without any manipulation of the data,  r(RI) can be...
SR Millis
srmillis
Offline Send Email
Oct 24, 2009
6:10 pm

Dear Scott R Millis Can you elaborate method of calculating Pearson's 'r' between continuous and ordinal variables without any manipulation of data? What is...
Nand Kishore Singh
nk_singh1
Offline Send Email
Oct 26, 2009
6:38 pm

This book does an excellent job of discussing this topic:   Chen, P., & Popovich, P. (2002). Correlation: Parametric and nonparametric measures. Thousand...
SR Millis
srmillis
Offline Send Email
Oct 26, 2009
6:56 pm

Dear Scott R Millis I hope Christian Schuster (who originated this discussion) may give more information about data. What I could understand is he want to...
Nand Kishore Singh
nk_singh1
Offline Send Email
Oct 28, 2009
2:16 pm

Nand,   I'm sorry but I don't have any web resources related to this version of Pearson r.   Alternatively, if your ordinal variable has relatively few...
SR Millis
srmillis
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Oct 28, 2009
9:24 pm

Dear Friend (1)You can use `encode’ command to change string variable to numeric variable.   (2) You can use rank correlation. In Stata there is command...
Nand Kishore Singh
nk_singh1
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Oct 25, 2009
5:21 am

Dear Christian You can use Point Biserial rpb correlation. For more information see http://www.andrews.edu/~calkins/math/edrm611/edrm13.htm#ETA   This link...
ehsan sabaghiayan
e_sabaghian82
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Oct 25, 2009
9:40 am
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