Difference between the interaction : and * term for formulas in StatsModels OLS regression
Hi I'm learning Statsmodel and can't figure out the difference between : and * (interaction terms) for formulas in StatsModels OLS regression. Could you please give me a hint to figure this out? Thank you! The documentation: http://statsmodels.sourceforge.net/devel/example_formulas.html Yaron ":" will give a regression without the level itself. just the interaction you have mentioned. "*" will give a regression with the level itself + the interaction you have mentioned. for example a . GLMmodel = glm("y ~ a: b" , data = df) you'll have only one independent variable which is the results of "a"