Reply #52: why misreporting of past votes matters

[OnTheOtherHand]

Here is a simple example of why misreporting of past votes affects the apparent "defection percentages." Of course, someone who is looking to evade the lesson of this example can complain that it isn't "realistic." That's true. It isn't designed to be realistic: it is designed to be simple.

Suppose we have information on 20 voters: whom they actually voted for in 2000 and 2004, and whom they say in 2004 that they voted for in 2000. In this simple example, a single Gore voter (#10) says that s/he voted for Bush. #10 also votes for Bush in 2004. Otherwise, one Gore voter votes for Bush in 2004, and one Bush (2000) voter votes for Kerry, a wash.

         actual    2004 report    actual
voter  2000 vote  of 2000 vote   2004 vote
  1      Gore        Gore         Kerry
  2      Gore        Gore         Kerry
  3      Gore        Gore         Kerry
  4      Gore        Gore         Kerry
  5      Gore        Gore         Kerry
  6      Gore        Gore         Kerry
  7      Gore        Gore         Kerry
  8      Gore        Gore         Kerry
  9      Gore        Gore         *Bush
 10      Gore       *Bush         *Bush
 11      Bush        Bush          Bush
 12      Bush        Bush          Bush
 13      Bush        Bush          Bush
 14      Bush        Bush          Bush
 15      Bush        Bush          Bush
 16      Bush        Bush          Bush
 17      Bush        Bush          Bush
 18      Bush        Bush          Bush
 19      Bush        Bush          Bush
 20      Bush        Bush        *Kerry

So, we have 10 Gore voters and 10 Bush (2000) voters; 9 reported Gore voters and 11 reported Bush (2000) voters; 9 Kerry voters and 11 Bush (2004) voters.

If we make a table based on actual vote in 2000, it will look something like this:

2000 vote (%)    Kerry %    Bush %
  Gore (50%)       80%        20%
  Bush (50%)       10%        90%

(The "defection" percentages are 2/10 = 20% for Gore-to-Bush and 1/10 = 10% for Bush-to-Kerry.)

But if we make a table based on reported vote in 2000, it will look something like this:

2000 vote (%)    Kerry %    Bush %
  Gore (45%)       89%        11%
  Bush (55%)        9%        91%

(The defection percentages are 1/9 = 11% for "Gore"-to-Bush and 1/11 = 9% for "Bush"-to-Kerry.)

So, in this simple example, the effects of overstating having voted for Bush are (1) to exaggerate the apparent share of Bush (2000) voters in the 2004 electorate, and (2) to understate the difference in defection rates between Gore voters and Bush voters.

Is this example too simple? Of course it is. That's why I wrote an entire paper exploring the quantitative dynamics, as well as presenting the empirical evidence for misreporting of past votes. The response?

*crickets*