bugPSPP - Bugs: bug #51146, Regression: r correlation...

 
 

bug #51146: Regression: r correlation coefficient sign error

Submitted by:  None
Submitted on:  Tue 30 May 2017 11:15:39 PM UTC  
 
Category: Numerical ErrorsSeverity: 5 - Average
Status: InvalidAssigned to: None
Open/Closed: ClosedRelease: None
Effort: 0.00

Add a New Comment(Rich Markup)
   

You are not logged in

Please log in, so followups can be emailed to you.

 

Thu 15 Jun 2017 02:52:30 PM UTC, comment #2:

Closing as invalid. If anyone thinks this is wrong. Please re-open.

John Darrington <jmd>
Project Administrator
Wed 31 May 2017 06:27:03 AM UTC, comment #1:

I think you are referring to the "R" in the left hand column of the "Model Summary" box. This is NOT the Pearson Correlation Coefficient.

It is nothing other than the square root of "R Square" which is a measure of how much variance in the model is explained by the predictor variables. Some authors call this "Multiple R^2".

In the special case of simple linear regression (when there is only one predictor variable) R does indeed have the same magnitude as that of the Pearson correlation coefficient, but it should not be regarded as the same value.

The coefficent "Beta" in your example is correctly given as -0.76
(-0.7556 if you increase the number of decimals in the output).

John Darrington <jmd>
Project Administrator
Tue 30 May 2017 11:15:39 PM UTC, original submission:

Hello:

In the example file I am attaching the correct result for the simple regression model is (as calculated using R):

y.hat = 0.5259 - 0.0001x

PSPP gives

y.hat = 0.53 + 0.00x

It might seem to be a matter of decimal digits, but main problem is PSPP gives the value of r (Pearson's correlation coefficient) as 0.76; but it is -0.76, so it has a problem with the sign of r and beta.hat1.

I am a teacher and this error pop up at my class yesterday. Could it be solved?

Anonymous

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach File(s):
   
   
Comment:
   

Attached Files
file #40816:  Memoria.sav added by None (1KiB - application/x-spss-sav - Files of data, results and a Word file with results obtained using R)
file #40817:  Resultados PSPP Retencion de Memoria 2017 05 29.pdf added by None (46KiB - application/pdf - Files of data, results and a Word file with results obtained using R)
file #40818:  Ejemplo Retención de memoria.docx added by None (29KiB - application/vnd.openxmlformats-officedocument.wordprocessingml.document - Files of data, results and a Word file with results obtained using R)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by jmd (Posted a comment)
  •  

    Do you think this task is very important?
    If so, you can click here to add your encouragement to it.
    This task has 0 encouragements so far.

    Only logged-in users can vote.

     

    Please enter the title of George Orwell's famous dystopian book (it's a date):

     

     

    Follow 5 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu 15 Jun 2017 02:52:30 PM UTCjmdStatusNone=>Invalid
      Open/ClosedOpen=>Closed
    Tue 30 May 2017 11:15:39 PM UTCNoneAttached File-=>Added Memoria.sav, #40816
      Attached File-=>Added Resultados PSPP Retencion de Memoria 2017 05 29.pdf, #40817
      Attached File-=>Added Ejemplo Retención de memoria.docx, #40818

    Back to the top


    Powered by Savane 3.1-cleanup1