evaluation of treatment efficacy in a cohort of people considering a single variable

#1
Hello, I have to evaluate the treatment efficacy in a cohort of people over a year (so I have 4 groups of data, one for each 3 months) considering a single variable. This variable is ordinal (goes from 0 to 9) and of course the 4 groups of data are referred to the same persons. Which statistic test shall I use? I thought about t-test (but which one?) but maybe theres something more appropriate.
I use SPSS.
thank you very much

example

followup t0 t1 t2 t3
.
person1: 2 4 4 5
person2: 1 3 2 5
person3: 0 0 1 1
....

p.s. I could also perform this statistic using a three year database, so the groups of data will be much more
 

rogojel

TS Contributor
#3
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

hi,
what is exactly the question you need to answer with the test?
regards
rogojel
 
#4
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

I can compare the cohort of person undergoing the threatment with another cohort undergoing a different one. basically the dataset is huge and some of them chose a treatment, some another, the rest went for placebo. For all of them the initial conditions were the same and there was a three months follow-up.
I need a test that makes me answer the question: which treatment is the best?
thank you so much :)
 

Karabiner

TS Contributor
#5
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

Could you describe your dependent variable in more detail? Maybe it could
be treated as an interval scaled measure.

How large are your 3 samples? And is it correct to assume that no randomization
was used to allocate subjects to groups?

With kind regards

K.
 
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#6
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

the samples contain more than 300 records each
the dependent variable is a score that is related to an effect. it goes from 0 to 9
yes, unfortunately no randomization has been done

thank you so much
 

Karabiner

TS Contributor
#7
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

the dependent variable is a score that is related to an effect. it goes from 0 to 9
I am afraid that this is not very informative. Is it a rating scale? A physical measurement?
Was it already used and validated in other studies? How was it treated there, always as
ordinal scaled?
unfortunately no randomization has been done
A repeated measures (mixed) ANOVA would be straightforward,
with time of measurement as within-subjects factor and group
as between subjects factor. But this assumes an interval scaled
dependent variable.

With kind regards

K.
 
#8
Re: evaluation of treatment efficacy in a cohort of people considering a single vari

your assumption was right about the variable. So the anova fits this dataset better? and what type of?