Sunday, January 27, 2008

Obama's South Carolina victory not simply a consequence of high black voter turnout

Brian has done some no-nonsense calculations showing that even with a black voter turnout as low as 18%, Obama would have won South Carolina.

Tuesday, January 15, 2008

Complete map of Diebold precincts

Here you go. Red is Diebold.

Diebold effect sticks around, need a proper statistician

I have incorporated Brian's work in my latest analysis. I tried different linear and generalized linear models combining Clinton's score, the total number of votes, the usual demographic data, employment rates, education and latitude and longitude.

I took the latest available data sets, got the list of towns using electronic voting from the official site, completed and corrected town names by hand.

The significant factors I found are, in order of decreasing signifiance:
  • Percent of people holding bachelor's degrees,
  • Voting method.
It is interesting to note that when with the new, improved data, the percent of people holding a bachelor's degree becomes extremely significant (about p = 3e-9 vs. about p = 0.001 for voting method.)

I'd like someone who know his statistics well to check the data and tell us if the voting method is indeed significant. The fitted models are linear and for all I know, it could be acting as a non-linear proxy for population size or some other funny explanation...

Anyway the new data is available here, feel free to check, improve and re-publish it. Note that you need the maptools R package. You can install it by typing install.packages(c("maptools", "maps"),dependencies=T)) in R.

Monday, January 14, 2008

Geographical explanation might not be as watertight after all...

Reddit user brfox has started his blog on election statistics and did some analysis taking the geographic distribution of states into account. It seems that there is still a Diebold effect.

Meanwhile a column at argues geography is the explanation.

We need to double- and triple-check check all this data carefully. If, after controlling for various parameters, we still have what looks like a statistical anomaly, we must get some expert opinion.

Request voting precinct geographical data

Hello all,

After brfox's message, I have been scavenging the net for a database that would allow me to map New Hampshire voting precincts.

I found some data at the USGS, however voting precincts do not match ZIP codes exactly. Also I need latitude/longitude data.

So I parsed the latlong data from Wikipedia, which lists 223 towns. Here it is, feel free to use it or to complete it.

We can do a paired study on adjacent voting precints with different methods, or do a regression analysis with latitude/longitude as extra data.

Strong geographical clustering of Diebold precincts

Someone from Reddit has just forwarded me a map showing that precincts using Diebold machines are geographically aggregated in the south-east of the state. Finally, this could be the explanation!

We still need to do a study of geographically and demographically similar pairs with distinct voting methods.