Re: Curious about K-S test in NPTESTS

Posted by Bruce Weaver on Dec 09, 2018; 10:12pm
URL: http://spssx-discussion.165.s1.nabble.com/Curious-about-K-S-test-in-NPTESTS-tp5737122p5737127.html

CROSSTABS also reports a Chi-square test of linear-by-linear association,
which you could use in this situation.  See David Howell's nice note on it
here:

https://www.uvm.edu/~dhowell/StatPages/More_Stuff/OrdinalChisq/OrdinalChiSq.html

By the way, for those who may not have heard, David Howell died on Oct 4 of
this year.  He'd been fighting cancer for about 8 years.  



Rich Ulrich wrote

> A likert-type scaling has order, and the ordinary contingency table
> does not respect that. You have a 2 d.f. test rather than a 4 d.f.
> test, and the /usual/ difference between distributions is the mean.
> Having a hole in likert-type responses (1s, least number of 2s, 3s,
> 4s, 5s) would be unusual and suspicious all by itself, but is among
> what the contingency table tests.
>
> If you want a test on variances, in addition to the usual test on means,
> the "powerful" manner of testing is to conduct two separate tests, each
> with 1 d.f.   I think it also would be clearer in a report on results to
> describe
> two tests.
>
> For the simple variance-ratio F-test, I get F=1.923, p < .001 (same
> p-report
> I gave for the 2x5 table).  With more precision: this one is p= 0.00069,
> while
> the 2x5 table was  p= 0.0008-something.
>
> --
> Rich Ulrich
>
> ________________________________
> From: Beckstead, Jason &lt;

> jbeckste@.usf

> &gt;
> Sent: Sunday, December 9, 2018 1:14 PM
> To:

> spssx-l@.uga

> ; Rich Ulrich
> Subject: Re: Curious about K-S test in NPTESTS
>
> Thanks to all. You guys confirmed my hunch. I guess that the best way to
> compare the difference between two or more distributions of 5 values (like
> those resulting from different sets of verbal anchors on Likert-type
> scales) is to use chi-square test.
> Jason
>
> sent via me phone
>
> ________________________________
> From: Rich Ulrich &lt;

> rich-ulrich@

> &gt;
> Sent: Saturday, December 8, 2018 8:19:14 PM
> To:

> SPSSX-L@.UGA

> ; Beckstead, Jason
> Subject: Re: Curious about K-S test in NPTESTS
>
> Your apparent difference is not location (mean), but "scale"
> (standard deviation). Since the K-S test is sensitive to both, it
> will not be especially powerful for either.
>
> A second generic problem is that rank-based tests, in derivation
> and in most casual discussion, assume that there are no ties -- but
> your data features only 5 values for 200 cases. Many ties. Sometimes
> having ties is mainly notable for making the test-values wrong (so,
> Jon's use of "exact stats" for p-level is good practice); sometimes,
> like here, it also is reflected in a weakened test.
>
> I put the 10 cells in a 2x5 contingency table, ignoring order, and the
> online calculator gave me X2= 18.83, p< .001 (4 d.f.), which looks okay.
>
> --
> Rich Ulrich
>
>
>
> ________________________________
> From: SPSSX(r) Discussion &lt;

> SPSSX-L@.UGA

> &gt; on behalf of Beckstead, Jason &lt;

> jbeckste@.usf

> &gt;
> Sent: Saturday, December 8, 2018 4:21 PM
> To:

> SPSSX-L@.UGA

> Subject: Curious about K-S test in NPTESTS
>
>
> Hi all,
>
> I am working to compare various sample distributions and thought that the
> Kolmogorov-Smirnov test in NPTESTS would be appropriate. However, it
> doesn’t reveal these two obviously different distributions as significant.
> Syntax is below. Any insight would be appreciated.
>
> Jason
>
>
>
> DATA LIST FREE/FORM X FREQ.
>
> BEGIN DATA.
>
> 1 1  7
>
> 1 2 24
>
> 1 3 38
>
> 1 4 24
>
> 1 5  7
>
> 2 1 20
>
> 2 2 20
>
> 2 3 20
>
> 2 4 20
>
> 2 5 20
>
> END DATA.
>
> WEIGHT BY FREQ.
>
> VARIABLE LEVEL X (SCALE).
>
> *Nonparametric Tests: Independent Samples.
>
> NPTESTS
>
>   /INDEPENDENT TEST (X) GROUP (FORM) KOLMOGOROV_SMIRNOV
>
>   /MISSING SCOPE=ANALYSIS USERMISSING=EXCLUDE
>
>   /CRITERIA ALPHA=0.05  CILEVEL=95.
>
>
>
> _____________________________________________________________
>
>  Jason W. Beckstead, Ph.D.
>
>   Associate Professor/Quantitative Methodologist
>
>   University of South Florida College of Public Health
>
>   13201 Bruce B. Downs Blvd., MDC56, Tampa, FL 33612, USA
>
>   Statistical Editor, International Journal of Nursing Studies
>
>   phone: [phone]  fax: [phone]
>
>   personal website:  http://personal.health.usf.edu/jbeckste/
>
>   International Journal of Nursing Studies  http://www.elsevier.com/ijns
>
>
>
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-----
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Bruce Weaver
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