Stata 12 to r how to#

TheД®ffects option difplays addition output including t-tests and p-values. The character indicates that we want this for each level of variable b. prefix indicates that we want to use reference category coding. In this example, we will contrasts versus a reference category for variable a (level 1) at each level We will begin with some simple contrasts, that is, one degree of freedom contrastsДЇor a variable run at each level of another variable. Okay, now weвЂ™re ready to explore this interacton. Now, LetвЂ™s plot these means using the marginsplot command that was also introduced in Stata 12. margins a#bД®xpression : Linear prediction, predict() Next, we will use the margins command to get the nine cell means. This is becauseДЄnova and regression are really two variants of the same linear model.

Not only is it significant, the F-ratio is identical to the anova results. Since we ran the model as a regression we need to check to see if the interactions is significant using the contrast command. However, regress assumes that the interaction of two variables involves factor variables so we could chave written the commandas follows: regress y a#b. We explicitly identified a and b as categorical (factor) variables. We want to demonstrate that the contrastД¬ommand works just as well with regression as it does with anova so we will rerun the model using the Many researchers run their analyses using regression methods.

The data are taken from Roger KirkвЂ™s (1995) We will begin by loading the data and running an anova model. In this presentation so that we can focus on the methods involving the contrast

Stata 12 to r how to#

We will not show how to adjust the p-values

Note: The techniques shown on this page are considered to ben post-hoc analyses.ДЄs such, they require the researcher to compute adjusted p-values for the various contrasts and tests. But, of course we cannot cover every possible method that is included in the This page will show some of the ways youД¬an explore interations. In this FAQ we will look at the contrast commandДЄnd shown how it can be used to explore interactons.