shri
☆    

2008-08-20 13:06
(5700 d 03:17 ago)

Posting: # 2201
Views: 9,601
 

 help [Nonparametrics]

the data is like given below where a, b, c, d are treatment given to subjects and the 0=cure, 1=mild, 2=modrate, 3=sevior

      |           subject
treat |    1    2    3    4    5    6
------+--------------------------------
  a   |    0    0    1    1    2    3
  b   |    1    1    2    2    3    0
  c   |    3    2    0    0    0    1
  d   |    2    2    0    0    1    1


what we can interprete about values separately for 0, 1, 2, 3.
please give me suggestion which type of nonparametric test we should use here.

thanks in advance.

--
Edit: Reformatted using BBCodes. [Jaime]

shri
Jaime_R
★★  

Barcelona,
2008-08-20 14:03
(5700 d 02:19 ago)

@ shri
Posting: # 2202
Views: 8,444
 

 n x k contingency table?

Dear Shri,

please see here.

Regards, Jaime
ElMaestro
★★★

Denmark,
2008-08-20 14:29
(5700 d 01:54 ago)

@ shri
Posting: # 2203
Views: 8,340
 

 help

Hi Shri,

❝ the data is like given below where a, b, c, d are treatment given to subjects and the 0=cure, 1=mild, 2=modrate, 3=sevior


Without being a stats shark I think this might be a candidate for the Friedman test. It seems illogical to me if a n x k contingency table is applicable here since (as far as I understand) the data are not counts but gradings.

EM.
Jaime_R
★★  

Barcelona,
2008-08-20 14:39
(5700 d 01:44 ago)

@ ElMaestro
Posting: # 2204
Views: 8,367
 

 help

¡ ElMaestro !

❝ Without being a stats shark ...


Me not either. :-D

❝ ... I think this might be a candidate for the Friedman test. It seems illogical to me if a n x k contingency table is applicable here since (as far as I understand) the data are not counts but gradings.


Yes, I think you're right. I guess the evaluation should be done for treatment, not for cure?

Regards, Jaime
statistician
☆    

India,
2010-06-30 16:26
(5020 d 23:57 ago)

@ ElMaestro
Posting: # 5579
Views: 7,789
 

 help

HI FRIENDS,

Here is my problem i am having a ordinal data (rating from 0 (success) to 5 (failure)) there are 5 variables to compare. i have to compare two groups also it is repeated measurements (8 weeks) sample size is 10. i just want to know which non-parametric method is applicable for comparing this multivariate data since we cannot use multivariate anova (parametric). suggestions and help is much appreciated.

thank you,
RK
martin
★★  

Austria,
2008-08-20 14:58
(5700 d 01:24 ago)

@ shri
Posting: # 2205
Views: 8,424
 

 help

dear shri !

The most important things regarding selection of a statistical tests is to
  1. define the null and the alternative hypothesis
  2. define your type I error
  3. define an adequate measure for the treatment effect(s) as confidence intervals are much more informative than plain p-values
and not looking for a test suitable for a given spreadsheet :no:

hope this helps

Martin

PS.: on the assumption that your null hypothesis is no treatment effect on your variable (which have to be defined exactly such as median score, proportions per score, etc. ) you may have the following alternatives
  • treatment arms are different
  • pairwise comparisons of treatments which results in a multiplicity problem
  • in case of a natural order of your treatment (e.g. dose levels) you may interested in the alternative of an increase/decrase as dose increase
  • you may have a dose-finding problem; ie. selection of the lowest / highest dose which differs from your control treatment which can be formulated as a sequence of hypothesis testing problems
  • etc. etc.
there is also the other way round in the case that you want to show non-inferiority or equivalence between two or more treatment arms (e.g. identification of the maximum safe dose).

as you can see it is very important that you are able to define your null and your alternative hypothesis.
shri
☆    

2008-08-20 15:26
(5700 d 00:56 ago)

@ martin
Posting: # 2206
Views: 8,408
 

 help

Thanks Martin,
but 0,1,2,3 are the some side effect of some imagenary drug,
and i want to interprete that some type of reaction was always there for that drug,
how can we analyse that through statistical manner?
and is there any other nonparametric methode which we use here?
thanks.

--
Edit: Full quote removed. Please see this post! [Jaime]

shri
martin
★★  

Austria,
2008-08-20 16:14
(5700 d 00:08 ago)

@ shri
Posting: # 2207
Views: 8,412
 

 help

dear shri !

first I would suggest a descriptive summary table showing percentage of scores by treatment

rows: treatment (a,b,c,d)
columns: scores (0,1,2,3)
cells: row percentages (total per treatment = 100%)

in the case that you are interested in a score of 3 between treatments I suggest to define a new variable with values of 0 (score<>3) and 1 (score=3). you may then calculate the treatment effect (odds ratio + corresponding confidence interval) between two treatments regarding the risk of experiencing a score of 3 (via logistic regression to model the whole data set like: new variable = treatment).

hope this helps

martin
d_labes
★★★

Berlin, Germany,
2010-06-30 18:16
(5020 d 22:06 ago)

@ shri
Posting: # 5580
Views: 7,836
 

 Higher order cross-over with ordinal response?

Dear Shri,

I presume this is a 4-period crossover study with four treatments, right?

Response is ordinal since your values are ordered categories.

You are interested in the differences (or equivalence?) between the treatments a, b, c and d, right?

I myself hadn't any such complicated, not an every-day-analysis to do in my career, thanks God :-D. It's therefore out of my feasibility to point you to the right statistical method.

But I have some tips for you (but only if my presumptions are fulfilled):
  • Treat your ordered categories (ranks) as metric (of course they are not :cool:) and use them in the ordinary evaluation via parametric ANOVA. This is what Helmut has suggested in this thread regarding non-parametric evaluation of tmax. This will give a rough "feeling" for treatment differences.

  • Read Chapter 6 "Analysis of Categorical Data" in
    Byron Jones, Michael G. Kenward
    "Design and Analysis of Cross-Over Trials"
    CHAPMAN & HALL/CRC
    Boca Raton, London New York Washington, D.C. (2003)
    Second Edition

    Read the paper
    Ezzet, F. and Whitehead, J.
    "A random effects model for ordinal response from a cross-over trial"
    Statistics in Medicine 10, 901-907 (1991)
    I'm not totally aware but it seems the keyword is "Logistic regression".

    And last but not least :google: with the keywords from the subject line of this post.

  • Consult a statistician of your very confidence who has "The power to know" with such a data analysis and outsource this analysis :-D.
Hope this helps.

Regards,

Detlew
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