Hi,
A first attempt to ask a question here in the forum, which I have otherwise used a lot to find solutions to coding issues.
My question is about the simanova command (https://stats.idre.ucla.edu/stata/ad...anova-hlp-htm/) that is used as an alternative to standrad ANOVA when there are different sized groups and variables with unequal variances.
I am having some difficulties with the output, as I get two rows with p-values from each analysis. Here is an extract from my code (this is, as you can see from the `x', part of a loop-code, where I analyse several variables in a number of different population groups):
***
simanova `x' row_individual, seed(74593) reps(5000) nomp(0.05) level(95) fstar wtest
…
Results of Standard ANOVA
----------------------------------------------------------------------
Dependent Variable is cost_drug and Independent Variable is row_individual
F( 7, 808.00) = 2.836, p= 0.0063
----------------------------------------------------------------------
5000 simulated ANOVA F tests
--------------------------------
Nominal Simulated Simulated P value
P Value P Value [95% Conf. Interval]
-----------------------------------------
0.0063 0.0090 0.0066 - 0.0120
0.0500 0.0614 0.0549 - 0.0684
…
***
The first row (yellow) appears to be somehow derived from the standard ANOVA-results, while the second row (green) is my selected “nomp-value” (which should be the nominal p-value, if I understand the help page correctly). Why do I get both and how can I interpret the different rows? Which is the correct one to report/use if I just want to know the p-value for this comparison of [drug] costs between groups? I have not found any information on this either here in the Statalist or in searching e.g., google. I hope someone here in the forum can guide me?
Kind regards,
Hanna Gyllensten, postdoc at the University of Gothenburg in Sweden
A first attempt to ask a question here in the forum, which I have otherwise used a lot to find solutions to coding issues.
My question is about the simanova command (https://stats.idre.ucla.edu/stata/ad...anova-hlp-htm/) that is used as an alternative to standrad ANOVA when there are different sized groups and variables with unequal variances.
I am having some difficulties with the output, as I get two rows with p-values from each analysis. Here is an extract from my code (this is, as you can see from the `x', part of a loop-code, where I analyse several variables in a number of different population groups):
***
simanova `x' row_individual, seed(74593) reps(5000) nomp(0.05) level(95) fstar wtest
…
Results of Standard ANOVA
----------------------------------------------------------------------
Dependent Variable is cost_drug and Independent Variable is row_individual
F( 7, 808.00) = 2.836, p= 0.0063
----------------------------------------------------------------------
5000 simulated ANOVA F tests
--------------------------------
Nominal Simulated Simulated P value
P Value P Value [95% Conf. Interval]
-----------------------------------------
0.0063 0.0090 0.0066 - 0.0120
0.0500 0.0614 0.0549 - 0.0684
…
***
The first row (yellow) appears to be somehow derived from the standard ANOVA-results, while the second row (green) is my selected “nomp-value” (which should be the nominal p-value, if I understand the help page correctly). Why do I get both and how can I interpret the different rows? Which is the correct one to report/use if I just want to know the p-value for this comparison of [drug] costs between groups? I have not found any information on this either here in the Statalist or in searching e.g., google. I hope someone here in the forum can guide me?
Kind regards,
Hanna Gyllensten, postdoc at the University of Gothenburg in Sweden
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