More Questions in Florida 13 - David Dill, Walter Mebane

Our results are suggestive but in important respects puzzling. In a
nutshell, the excessive CD-13 undervote rate in Sarasota County is not yet well-understood,
and will not be understood without further investigation. On its own, further statistical
analysis of the kind of data we examine here probably cannot explain the undervotes

We find differences of hundreds of CD-13 undervotes
when we compare voting machines that have different observable characteristics.
Hundreds of these undervotes are related to a specific error message in the event log file (the event
log file supposedly reports every transaction that occurred on each voting machine)...

The principal question we cannot answer is whether these patterns reflect voluntary behavior
or artificial errors or manipulations. The urgency of this question is highlighted by the fact that the relationship between the CD-13 undervote rate and the statewide office voting pattern differs depending on whether a particular error message occurs on the voting machine on which the votes were cast....

http://macht.arts.cornell.edu/wrm1/smachines1.pdf