bugPSPP - Bugs: bug #59111, Examine: Spreadlevel plot does not...

 
 

bug #59111: Examine: Spreadlevel plot does not accept float t values / Power Estimation

Submitted by:  Friedrich Beckmann <beckmanf>
Submitted on:  Sun 13 Sep 2020 10:58:05 PM UTC  
 
Category:  Syntax Parser Severity:  5 - Average
Status:  None Assigned to:  None
Open/Closed:  Open Release:  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.

 

Sun 13 Sep 2020 10:58:05 PM UTC, original submission:  

While doing the examine plot subdialog I noticed two problems with the spreadlevel plots.

a) The syntax parser only accepts integer value for the t value. This does not allow to compute square root (0.5) or reciprocal square root (-0.5) scalings of the data although this seems to be a reasonable thing to do.

see: http://www.unige.ch/ses/sococ/cl/spss/eda/spreadlevelplot.html

b) I think there is a difference in the understanding between SPSS and PSPP with respect to the spreadlevel plot, but I am not sure. Here is the SPSS description:

SPREADLEVEL(n). Spread-versus-level plot with the Test of Homogeneity of Variance table. If the keyword appears alone, the natural logs of the interquartile ranges are plotted against the natural logs of the medians for all cells. If a power for transforming the data (n) is given, the IQR and median of the transformed data are plotted. If 0 is specified for n, a natural log transformation of the data is done.

see: https://www.ibm.com/support/knowledgecenter/SSLVMB_sub/statistics_reference_project_ddita/spss/base/syn_examine_plot.html

The gui has a selection "Power Estimation" and that refers to the mode: "If the keyword appears alone, the natural logs of the interquartile ranges are plotted against the natural logs of the medians for all cells."

Is "Power Estimation" different from SPREADLEVEL(0) ? In the PSPP docs this is the same. But aren't the natural logs of the interquartile ranges different from interquartile ranges of transformed data?

Friedrich Beckmann <beckmanf>
Project Member

 

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

Attach Files:
   
   
Comment:
   

No files currently attached

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by beckmanf (Submitted the item)
  •  

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

    Only logged-in users can vote.

     

     

     

    No changes have been made to this item

    Back to the top


    Powered by Savane 3.5