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help for ^pre^ - 1.0 - 17 Mar 2005
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Calculate the Proportional Reduction in Errors achieved by the model
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^pre^ [^, ^c^utoff(#) ]

Description
-----------

^pre^ is a post-estimation command that calculates the proportional reduction i
> n
errors achieved by the model.  pre is a measure of the predictive power of a mo
> del.
This routine is simpler and is applicable to more models than lstat.

The approach of this procedure has three steps
1. find the errors when guessing without the model = E1
2. find the errors when guessing what the model predicts = E2
3. PRE = (E1-E2)/E1 */

For categorical dependent variables, the errors without the model are found by
guessing the mode.  The errors made without the model are: E1=N-Mode

For continuous dependent variables, the errors without the model are found by
guessing the mean. The errors without the model are E1=(Y-Ybar)^2.  For OLS
models pre = R2.

Options
-------
^c^utoff(real) is the cutoff probability for logistic regression, i.e. the
value above which the prediction is 1.  The default is 0.5.

Examples
--------
. regress cbecs09 cprcs03 cprcs05
. ^pre^

Author: Paul Millar
www.ucalgary.ca/~pemillar/stata.htm
pemillar@@ucalgary.ca