What is IX in Stata?
By contrast, i.x notation tells any Stata regression command (and many non-regression commands as well) that the variable x is to be regarded as a discrete categorical variable and that each category (except one reference category) is to be represented in the model by a virtual indicator variable.
How do I create a dummy variable in Stata panel data?
There are three ways to create dummy variables: one is to use generate, which creates one dummy variable at a time; another is to use tabulate, which creates whole sets of dummies at once; and the third is to use xi, which may allow you to avoid the issue of dummy-creation altogether.
What does XI mean in Stata?
Description. xi expands terms containing categorical variables into indicator (also called dummy) variable sets. by creating new variables and, in the second syntax (xi: any stata command), executes the specified. command with the expanded terms.
Can you interact two dummy variables?
3 Answers. Sure, you can include an interaction between categorical variables in your regression. The interpretation is particularly easy if the categorical variables are binary (i.e. have only two categories).
What is Testparm Stata?
testparm provides a useful alternative to test that permits varlist rather than a list of coefficients (which is often nothing more than a list of variables), allowing the use of standard Stata notation, including ‘-‘ and ‘*’, which are given the expression interpretation by test. test and testparm perform Wald tests.
What does XI Reg do in Stata?
xi provides a convenient way to convert categorical variables to dummy or indicator variables when you fit a model (say, with regress or logistic).
What is Ovtest?
The estat ovtest command runs the RESET (regression specification-error test) for omitted variables. The RESET tests the model to ensure that omitted variables are not causing model misspecification. For a slightly less brief over view of the theory, see this google book result.
What does Bysort in stata do?
by and bysort are really the same command; bysort is just by with the sort option. performs the generate by values of pid but first verifies that the data are sorted by pid and time within pid. sort specifies that if the data are not already sorted by varlist, by should sort them.
What is exp required in stata?
varlist required = exp required using required by() option required Certain commands require a varlist or another element of the language. The message specifies the required item that was missing from the command you gave. See the command’s syntax diagram.