How the "PR" Quota System Works
Proportional representation or PR is the form of voting used by Cambridge under the Plan E form of government. Under PR a candidate needs to win a certain proportion of the the votes to be elected. This winning fraction of the votes is referred to as the "quota".
The quota is determined by dividing the total number of valid ballots cast by the number of positions to be elected plus one and then adding one to the resulting dividend.
Thus, to elect 9 City Councillors, the total number of valid ballots cast is divided by 10; to elect 6 School Committee members, the total is divided by seven. And in both cases 1 is added to the result of the division.
For example, if 25,000 valid ballots are cast for City Council, the quota will be 2,501 (25,000 divided by ten, plus 1).