Does anybody no how can I choose one of my independent variables of logistic regression as variable with OR=1?
I cannot find "reference variable" in dialog boxes of Stata. Is it the same with "omitted variable" and "offset variable"?
Type help fvvarlist into Stata's Command window, then scroll down to Base Levels and start reading.
Dear weaver,
I found this, however I wanted to perform it in the menus!
Base levels
You can specify the base level of a factor variable by using the ib. operator. The syntax is
Base
operator(*) Description
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ib#. use # as base, #=value of variable
ib(##). use the #th ordered value as base (**)
ib(first). use smallest value as base (the default)
ib(last). use largest value as base
ib(freq). use most frequent value as base
ibn. no base level
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(*) The i may be omitted. For instance, you may type ib2.group or b2.group.
(**) For example, ib(#2). means to use the second value as the base.
Thus, if you want to use group=3 as the base in a regression, you can type
. regress y i.sex ib3.group
You can also permanently set the base levels of categorical variables by using the fvset command.
See the attached image for info on how to set the base level via the GUI.