Open rnesti opened 2 years ago
Hi @rnesti,
Thanks for this suggestion. I agree that this would be a useful addition. However, it will take a significant amount of time to implement and test, and it is therefore unlikely to be implemented in Pingouin in the near future. I know that there is a Contrast module in statsmodels, have you looked into it?
Thanks, Raphael
Hi @raphaelvallat,
You're welcome!
Yes, I know the Contrast
site of statsmodels
. Sadly, It is also not possible to use the proper contrasts for planned contrasts. To get silimar results to JAMOVI
you have to use the Sum
contrast in the formula-based statsmodels
:
import statsmodels.formula.api as smf
linear_model = smf.ols(" Y ~ C(X1, Sum) * C(X2, Sum)" , data = data)
However, the problem is that you can't use additional contrasts, so the categoricals are "blocked" with the Sum
contrast. A workaround would be to use the models t_test()
function and pass it the contrasts like:
linear_model.t_test([2,-1,-1,0,0])
But this isn't working, because you are not able to access the reference levels. You could then use -1
to remove the Intercept
but then the Intercept
will be replaced with the mean of the first factor.
Best regards!
Hi @raphaelvallat,
Could you please add a possibility to test (planned) contrasts ?
Referring to Andy Field's
Goggles.sav
example from previously:What I could imagine would be a function
planned_contrasts()
used like:which would compare
Placebo vs. Low dose & High dose
.Changing
contrasts
to[0,-1,1]
would copareLow dosis vs. High dosis
Other contrasts would also be cool :)
Thank you very much!
Best regards!