Description
The data are observations on the difference between Democratic and
Republican vote counts, by (a) absentee ballot and (b) voting machine,
for 22 elections in Philadelphia's senatorial districts over the last
10 years.source
Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A
Course in Methods of Data Analysis (2nd ed), Duxbury.