Good luck in your work,

The simple solution would be to run many non-paired wilcox on all the 20
questions (the way Dieter suggested).
In which case, make sure to adjust for multiple comparisons.  Read about it,
and see:
?p.adjust
If you have some questions you can merge (by a simple mean of them), it will
probably do you good (using PCA might be an option, but it could also be an
over kill for you).


You might also be interested in plotting your data, here is a nice simple
hack on how to display the Correlation scatter-plot matrix for your data:
http://www.r-statistics.com/2010/04/correlation-scatter-plot-matrix-for-ordered-categorical-data/


And Dieter, thanks for a great quote: "Assess independence, equalvariance
and normality -in that order" (van Bell, Statistical rules of thumb)."


Tal


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On Mon, Apr 19, 2010 at 2:07 PM, Mona_m <purplemind@blueyonder.co.uk> wrote:

>
> Hi,
>
> I have just found this forum, and it looks like a great place to get some
> help (I hope)
> For my dissertation, which is due way too soon, I am doing a survey,
> comparing attitudes of 2 independent groups, with 5 scale likert questions.
> Basically I want to show if they have similar or different attitudes. I am
> testing 4 hypotheses, and have in total about 20 questions.
>
> I have to say my statistic skills are very basic and very rusty, we had
> some
> lectures two years ago, where we were introduced to R. I looked through my
> notes, and back then we did a one sample t-test to analyse likert type
> questions. I believe I would need to do a 2 sample unpaired t-test.  It
> would be great if someone could give me some feedback if this test is the
> most suitable one for my purpose, and maybe could explain to me what’s the
> easiest way to do this in R?
>
> You would help me loads!!
> Many thanks in advance
> Mona
>
> --
> View this message in context:
> http://n4.nabble.com/comparing-attitudes-of-2-groups-likert-scales-tp2015738p2015738.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@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.
>

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