Residual Votes in the Iowa 2006 General Election: Relationship to Voting Systems Used by Iowans for

1
Residual Votes in the Iowa 2006 General Election
Relationship to Voting Systems Usedby Iowans
for Voting Integrity

2
Key Findings

• In all 3 competitive statewide races in Iowa's
  2006 General Election
• Counties that used only paper ballots read by
  optical scanners had the lowest residual vote
  rate.
• Counties that used a blended voting system
  (primarily paper ballots read by optical scanners
  along with one touch screen per polling place)
  had the second-lowest residual vote rate.
• Counties that used only touch screens in the
  polling place had the highest residual vote rate.
• In the blended counties (with one touch screen
  per polling place), the residual vote correlated
  strongly with the rate of touch screen use.

3
Residual Votes Are Used to Evaluate Voting System
Effectiveness

• The residual vote rate, the difference between
  the number of ballots cast and the number of
  valid votes cast in a particular contest, is
  viewed by many experts as the single best measure
  of the effectiveness of a voting system.
• The Machinery of Democracy Usability of Voting
  Systems. Report of the Brennan Center for
  Justice at New York University Law School, p.1.
  Published on the Internet at http//www.brennance
  nter.org/dynamic/subpages/download_file_38889.pdf

4
Iowa's Voting Systems in 2006

• In the 2006 General Election, Iowa counties used
  one of three types of voting system
• 19 counties used only touch screen electronic
  voting machines (DREs) in the polling place.
• 21 counties used only paper ballots read by
  optical scanners. These counties served voters
  with disabilities with a ballot-marking device.
• 59 counties used a blended system, with one touch
  screen (DRE) used in each polling place and one
  paper ballot scanner. A majority of votes in
  these were cast on paper ballots, with the rate
  of touch screen use varying from county to
  county.
• Source Iowa Secretary of State's Web site,
  http//www.sos.state.ia.us/pdfs/elections/CoVoteSy
  stem.pdf

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5
Residual vote rates in Iowa 2006 general
election, as function of voting system. Means
for counties using all paper ballots (optical
scan), counties using all DREs (touch screens),
or a blend (mostly paper ballots, with one touch
screen per polling place).
6
Residual vote rate in Iowa 2006 general election.
Means for blended counties with varying levels
of DRE usage.
7
Residual vote rate vs. DRE use rate in 59 blended
counties. 2006 Iowa race for Governor. There is
a statistically significant correlation (r0.55,
df57, plt0.0001)?.
8
Residual vote rate vs. DRE use rate for 59
blended counties. 2006 Iowa race for Secretary of
State. There is a statistically significant
correlation (r0.33, df57, p0.01).
9
Residual vote rates vs. DRE use rates for 59
blended counties. 2006 Iowa race for Secretary of
Agriculture. There is a statistically significant
correlation (r0.37, df57, p0.004)?.