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Showing posts from April, 2010

Imputation of "e"

I'm finishing up a presentation that I'll be giving at AAPOR (Saturday, May 15th at 2:15) on using imputation methods to estimate "e." I posted on this topic a while ago. I wanted to post one of the graphics that I developed for that presentation.

I start from a very simple model that predicts eligibility using the natural logarithm of the last call number as the only predictor. That generates the following distribution of imputed eligible cases.

The blue line shows the eligibility rates for the cases for which the eligibility status is known. The blue dashed line shows the model (a logistic regression model predicting eligibility using the natural log of the call number) prediction of eligibility. The green line shows the eligibility for the cases where the eligibility flag is imputed. The green line is the line used to estimate "e."

Manual override II

We figured out a way to record every time a sample line is manually pulled up and called. As I mentioned in a previous post, I was concerned that this type of "manual override" might confound the results of an experiment we've been doing that compares different call scheduling algorithms.

The good news is that it happens very infrequently. There were 166 such calls in March and 153 in April. In any given month, there are 13,000 to 14,000 calls made. So these manual overrides are a pretty insignificant (about 1%) part of that effort. In addition, they don't seem to concentrated in one experimental arm over another.