Here’s a bloc FPTP election to make the point: suppose you have 3 candidates A, B, and C, and 3 voters. 2 of the 3 voters vote for A and B, and the third voter votes for C. Before even showing you the results, if A got 2 out of 3 voters to pick them, what % of votes would you expect them to get?
It turns out, they actually got 40%, not 67%! The reason is that most election results calculate a candidate’s vote percentage as votes cast for that candidate divided by votes cast for all candidates. So here, 2 votes for A + 2 votes for B + 1 vote for C = 5 votes for all candidates. The 2 votes A got are divided by the 5 votes for all candidates to be 40%. This problem applies to all “vote for one or more” elections, whether they have a limit on how many you can vote for or not.
The solution is to look at the number of total ballots cast in the election, not votes cast for all candidates. 3 people voted, so that’s 3 ballots cast in that election, and by dividing A’s 2 votes by those 3 ballots cast, we get the 67% reflection of support A deserved.
This is one more reason you can use in favor of a bloc Approval/Score (or even Approval/Score PR) ballot measure: even if a voter isn’t moved by Approval Voting itself, giving all candidates a more accurate reflection of support is something voters and candidates alike can agree on. This is actually a provision that made it into the Fargo ballot measure:
Reporting of results
For each candidate’s result in each race, reported vote percentages must be calculated by taking the number of votes for that candidate divided by the total ballots cast.
though not the St. Louis measure.