[Limdep Nlogit List] Nlogit crosstabs

Durham, Cathy cathy.durham at oregonstate.edu
Tue Aug 24 08:21:28 EST 2010

I've come to the realization that the actual v. predicted table produced from the ;crosstab 
statement with an nlogit run is not what I expected. I reproduced the values resulting from
 by writing out the formulas to create predictions and they are what I expected, but using the same principles to replicate the crosstab output does not. One would think the correctly predicted numbers would be the same. 
However since the row and and column totals are the same in the crosstab table this is something else.

The Nlogit 3.0 reference manual (p.N3-21) says the predictions are  obtained as the
Integer part of the formula
Sum over t P^ sub jt times y sub jt

What exactly are P^ and y  in this formula?
Is t the choice set, and is j the alternative?

In the printout tabulations are headed with the following.
	    | Cross tabulation of actual vs. predicted choices.    |
          | Row indicator is actual, column is predicted.        |
          | Predicted total is F(k,j,i)=Sum(i=1,...,N) P(k,j,i). |
          | Column totals may be subject to rounding error.      |

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