[R] Poly Correlations

[Ista Zahn]

Hi Michael,

See comments in line.

On Wed, Sep 4, 2013 at 10:18 PM, Michael Hacker <mhacker at nycap.rr.com> wrote:
> Dear Colleagues,
>
>
>
> I'm working on a Delphi study comparing perceptions of high school
> technology teachers and university engineering educators about the
> importance of concepts about engineering for HS students to learn as part of
> their fundamental education. I'm actually doing this as part of my Ph.D.
>
> The survey items (n=37) are categorized into five scales: design, human
> values, modeling, resources, and systems thinking. I'm seeking to determine
> the reliability of these scales and of the overall survey instrument. Since
> I'm working with ordinal data, Chronbach's Alpha probably isn't the best
> statistical tool to use.
>
>
>
> I've literally spent several days learning my way around R-project but am
> struggling with procedures and interpretations.
>
>
>
> I'm aware that there is now a plug-in for R for SPSS that can be downloaded
> ( <http://www-01.ibm.com/support/docview.wss?uid=swg21477550>
> http://www-01.ibm.com/support/docview.wss?uid=swg21477550 and
> <http://gruener.userpage.fu-berlin.de/Essentials%20for%20R%20Installation%20
> Instructions_21.pdf>
> http://gruener.userpage.fu-berlin.de/Essentials%20for%20R%20Installation%20I
> nstructions_21.pdf). Just learned that today and I downloaded
> PolyCorrelations.zip from
> https://www.ibm.com/developerworks/community/files/app?lang=en#/file/9f47f9a
> 0-7793-4ad5-8bb7-d3fd1a028e44
>
>

I would ditch the SPSS/R integration and just run R from RCommander.
You don't need PollyCorrelations.zip or SPSS for this, and trying to
get the R and SPSS talking to each other is just another level of
complication that you don't need.

>
> I've gotten as far as loading Rcmdr and running some analyses - (Statistics,
> dimensional analysis, scale reliability) and I've generated this output:
>
>
>
> Reliability deleting each item in turn:
>
>                         Alpha   Std.Alpha   r(item, total)
>
> design              0.8445    0.8490         0.7629
>
> humanvalues   0.8526    0.8541         0.7170
>
> modeling          0.8511    0.8546         0.7271
>
> resources        0.8712    0.8757         0.6328
>
> systems           0.8461    0.8498         0.7488
>
>
>
> I now would sincerely appreciate some help. At the age of 70, never having
> studied programming, the meaning of these statistics is not apparent.

Understanding these statistics has nothing to do with studying
programming. You need to study statistics!

>
> For example, I'm not clear if either of these three statistics are Ordinal
> Alpha. Since I'm working with Likert scale items, my advisor suggested that
> I seek an alternative to Chronbach's Alpha to determine reliability.

Since we have no idea how you calculated these statistics there is no
way for us to answer this question.

>
>
>
> So far, here are the steps I have taken:
>
> I've searched the FAQs
>
> Searched specifically for answers on the Web
>
> Played with the software for hours
>
> Read the accompanying documentation.
>
> Downloaded and installed Rcmdr
>
> Downloaded and installed PolyCorrelations.
>
>
>
> I tried running PolyCorrelations  but I get a message that states that this
> requires the Polychor and Gclus libraries. I tried to install them into the
> R console, but no luck.

What does "no luck" mean?

>
>
>
> I'd also be pleased to work with someone-on-one on a consulting basis if
> someone has the time and inclination.  Hoping to find an individual who
> knows SPSS and R.

Appendix B of http://pareonline.net/pdf/v17n3.pdf shows how to
calculate reliability from ordinal data using R.

Best,
Ista


>
>
>
> Thanks very sincerely for considering this request.
>
>
>
> Michael
>
>
>
>
>
> --------------------------------
>
> END OF MESSAGE
>
> --------------------------------
>
> Michael Hacker, Co-Director
>
> Hofstra University Center for STEM Education Research
>
> Ph: 518-724-6437
>
> Cell: 518-229-7300
>
> Fax: 518-434-6783
>
> URL: www.Hofstra.edu/CSR
>
>
>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.