[R] Not enough predicted values from pscl package?

Noah Silverman noahsilverman at ucla.edu
Wed Apr 10 06:24:49 CEST 2013


I'm used the pscl library to fit a zero inflated poisson model.

My data has 25,327 rows (no missing values.)

zeroinfl(y ~ x)  works fine.  I get coefficients, etc.

Now, I want to see the fitted values and do some comparisons to the truth.  So I used:

predict(mod, type="count)

The resulting vector only contains 25,213 values.  So, somehow, the predict function skipped predictions for several of my data points.  The problem is I don't know why and I don't know which values were skipped.  

Any suggestions?

Noah Silverman, M.S.
UCLA Department of Statistics
8117 Math Sciences Building
Los Angeles, CA 90095

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