Re: CTables Test of Significance

Posted by Bruce Weaver on Mar 28, 2017; 7:39pm
URL: http://spssx-discussion.165.s1.nabble.com/CTables-Test-of-Significance-tp5734016p5734023.html

Thom Baguley, whom some of you might know from other discussion forums, has written a blog post entitled "Beware the Friedman test!"

  https://seriousstats.wordpress.com/2012/02/14/friedman/

Here is an excerpt that captures one of Baguley's main problems with the Friedman test.

"The ranks for the Friedman test depend only on the order of scores within each participant – they completely ignore the differences between participants. This differs dramatically from the Wilcoxon test where information about the relative size of differences between participants is preserved. Zimmerman and Zumbo (1993) discuss this difference in procedures and explain that the Friedman test (devised by the noted economist and champion of the ‘free market’ Milton Friedman) is not really a form of ANOVA but an extension of the sign test. It is an impostor."

Cheers,
Bruce

Rich Ulrich wrote

Someone should mention that likert-type scorings are usually analyzed by assuming that

the scores are sufficiently equal-interval to justify ordinary ANOVA. By that token, you have

an ordinary repeated measures design.  Cautious testing between pairs will use paired t-tests.


Are you happy to describe the "average satisfaction" for a Jeep model?  If not, that would

justify considering the models with transformations.


To treat the rankings of each individual's scores -- a nonparametric, "ordinal" approach -- the

overall test would be Friedman's two-way ANOVA. Follow that with the non-parametric version

of a test.


Those logit or probit models will do better when you do not have large numbers of ties, that is,

when you start with continuous scores that always give unique values for ranks.

--

Rich Ulrich

________________________________
From: SPSSX(r) Discussion <[hidden email]> on behalf of Willbaileyz @ E <[hidden email]>
Sent: Monday, March 27, 2017 3:52:22 PM
To: [hidden email]
Subject: CTables Test of Significance


Monday morning blank ...

I have a set of variables say different Jeep models like Compass, Wrangler, Cherokee .... and for each a respondent does a rating from Very Satisfied - Very Unsatisfied (Ordinal from 1 to 5) and want to do a test of sig between the rating for each model.

For the life of me am blanked. In Ctables can set that x'tab up but since I reposition the response codes from the brand to the column test of sig want work

What am I missing

Running V24.0.0.1

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