st: Using Cronbach's alpha to generate sub scales.

[Francis Owusu <fowusu@iastate.edu>]

Hi all,

I need help using Stata to calculate Cronbach's alpha. I have data on 
different measures of performance and I want to group them into subgroups 
for further analysis. I have 2 problems:

1. Several of the questions were in negative, however in many cases, the 
negatives were not reversed in the calculation even though I did not 
include "asis" command. Any suggestions?

2. All of the survey questions are not on the same scale, so I include 
"std" command to standardize the items before summing. However, the new 
variable generated for the new scale had many negative scores.  I know that 
the scale should not be in negative. What would you advise?

Thanks

Francis Owusu
Department of Community & Regional Planning
Iowa State University
Ames IA, 50011




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