Evaluative Satisfaction System (Pacifica)

The Evaluative Satisfaction System (ESS) is a mixed electoral system under which representatives are elected in a two-step process with a single round of combined approval voting. Representatives are first chosen for on a constituency level (which might comprise the entire electorate as a single constituency, albeit this would be impractical in large-scale elections), after which the overall result is made more proportional by electing further representatives for underrepresented parties according to a best-loser algorithm on the basis of the constituency results. It was first developed for and used in the 2012 Tepertopian Assembly election with the intention to incentivize voting honestly rather than strategically.

ESS is a semi-proportional electoral system, since parties might win more constituencies in the first step than they would be proportionally entitled to in total, and the system does not compensate this by awarding other parties leveling seats to make a purely proportional result possible again.

Procedure

Under ESS, each voter casts a single combined approval voting ballot: Any number of candidates they approve or disapprove of may be marked (called "approved" and "vetoed" in Tepertopian electoral law), also with the option to avoid marking ("evaluating") a candidate altogether. Candidates may be linked to a party or stand as independents.

First Step: Constituency Seats

In the first step of the election procedure, representatives are determined on the constituency level. Each constituency elects at least one local representative, but there is no theoretical limit on the number of representatives a constituency could elect. There isn't a strict need to have multiple constituencies, either - for small-scale elections, there might also be just a single constituency, but a usually exponentially greater number of candidates per additional seat limits the practicability of single-constituency elections.

To determine the elected representatives, the absolute number of approvals and disapprovals on each candidate is tallied. The candidate(s) having the highest number of approvals after subtracting the number of disapprovals received are elected as the representative(s) of the constituency. This majoritarian method of selecting constituency winners tends to produce landslide victories for the candidates of the most-supported party on the constituency level, as long as none of them are so relatively more disliked by the electorate that their number of disapprovals pushes them below other candidates.

As an alternative to the majoritarian method, the Tepertopian Electoral System commission (TESC) also suggested electing constituency winners proportionally by using the sequential proportional approval system; this however was not adopted by the Tepertopian Assembly.

Second Step: Compensatory Seats

The second step of the procedure is more complicated. First, the parties eligible for compensatory seats have to be determined - the TESC suggested either using a traditional electoral threshold, which would eliminate all parties whose candidates didn't, on average, surpass a set approval percentage, or to require that at least one representative of the party had to be elected in a constituency; the latter of which was adopted.

Once the eligible parties have been determined, the ballots need to be re-counted in a manner similar to the satisfaction approval method: All approvals a voter gave out to candidates standing for eligible parties are assigned an equal share of the voter's "satisfaction" - essentially, their one vote is divided among all such candidates. The satisfaction thusly assigned to the candidates is then summed for each associated party, thereby determining the party's percentage of the satisfaction (vote) total. The party's share of total satisfaction is equal to the share of seats entitled to.

Finally, the compensatory seats are handed out iteratively: Until all seats are filled, the party with the greatest difference between its share of seats entitled to and current actual seat share is selected, and from among its non-elected candidates, the one with the lowest percentage of disapproval - relative to the total number of ballots cast in the respective constituency - is elected to a compensatory seat. In the Tepertopian implementation, this level of the election features regional divisions with a fixed number of compensatory seats assigned to each as well in order to prevent disproportionate regional representation arising from the second step of the election: Once enough candidates from that region have been elected to compensatory seats, the region becomes barred from electing any more candidates for the second step, effectively removing all candidates within its boundaries from the lowest-disapproval consideration.

Example

The constituency of Examplington encompasses the entire eponymous city, for which the three-seat municipal council is to be elected using ESS. Two parties (green and yellow) and one independent vie for the votes of the ten voters. Two of the three seats are to be elected in the first, the remaining one in the second step.

The ballots come in as follows:

Ballots Candidate	4×	3×	2×	1×
. A	✓
. B	✓	✗	✗
. C	✗	✓		✗
. D		✓	✗	✓
. E			✓	✓
Approval = ✓ \| Disapproval = ✗

First Step

According to the results above, the candidate's net approval scores are as follows:

Candidate	Approvals	Disapprovals	Net Approvals
. A	4	0	+4
. B	4	3 + 2 = 5	-1
. C	3	4 + 1 = 5	-2
. D	3 + 1 = 4	2	+2
. E	2 + 1 = 3	0	+3

As candidates A and E have the highest net approval, they are elected as representatives in the first step.

Second Step

For the purposes of demonstration, Examplington does not impose any hurdles for parties to take before qualifying for compensatory seats. The independent E however does not play any role for the second step, since only party-affiliated candidates are considered for the satisfaction division - the two voters whose only positive approval was for E are consequently completely removed from second step calculations.

As such, voter satisfaction for each of the ballots divides as such:

Ballots Candidate	4×	3×	1×	Satisfaction	Party Satisfaction
. A	0.5			2	4
. B	0.5			2	4
. C		0.5		1.5	4
. D		0.5	1	2.5	4
Satisfaction total:					8

In terms of satisfaction, the parties are split evenly - which makes sense considering that there were four ballots from voters only supporting the green party, three only supporting the yellow party, and one that supported a yellow party candidate and the independent. These shares of the total satisfaction determine the further procedure of the compensation algorithm, which runs the following steps once per seat to fill - in this case, only a single time, since only one seat remains to be filled on the council: First, the current share of seats each party has is determined, and then, the party with the greater difference between entitled and current seat share is awarded the seat.

Party	Current Seats	Current Share	Entitled Share	Difference
Green	1	33%	50%	12%
Yellow	0	0%	50%	50%

As the yellow party is more under-represented than the green party, it is awarded the seat. Inside the party, the seat goes to the least-disapproved candidate from among the constituency candidates - in this case, candidate C from the yellow party received 5 disapprovals, and candidate D received 2. As such, the final seat is filled by candidate D.

This means that the municipal council of Examplington will have A from the green and D from the yellow party, as well as the independent E.

Differences to Other Voting Systems

MMP

Unlike the Mixed-Member Proportional system, ESS does not natively accomodate for overhang seats - since the system works on an iterative, relative share basis with a fixed number of seats, other parties are actively harmed by a party winning more seats on the constituency level than it would be entitled to in the compensation step: If a party would be entitled to 50% of the seats, but its competitor already won 60% in constituencies, a 100-seat parliament would be split 60-40 in seats under the ESS, while MMP would still award the party its absolute 50 seats, for a final 60-50 seat split. Some versions of MMP would furthermore fully compensate overhang seats with leveling seats for the other parties, which would result in a fully proportional 60-60 seat split in the former example. Effectively, the ESS sacrifices this full proportionality in order to avoid ever-growing seat numbers stemming from overhang and leveling seats.

Furthermore, most MMP implementations separate the candidate and the party vote, allowing voters to support local candidates without giving votes to the associated party (split ticket), whereas ESS only exposes the candidates to voter approval and automatically converts their performance to party support to avoid decoy lists. However, ESS gives voters more options for influencing the order in which compensatory seats are awarded to candidates by using their disapproval count, whereas MMP usually features a closed party list, with the political parties fixing the order in which they want to have candidates elected in advance.

AMS

ESS is very similar to the Additional-Member System, which works the exact same on the overhang seat issue - essentially, ESS can be considered a sort of AMS, adapted to the use of Combined Approval Voting. However, AMS too often features split-ticket voting and closed party lists.

MMM

Mixed-Member Majoritarian systems differ from ESS in the way the proportional seats are handed out, since under MMM, both constituency and proportional seats are considered completely separately: A party may win every single constituency seat and still receive its share of the proportional seats. ESS on the other hand considers the whole seat total to be shared proportionally; accordingly, the seats a party has won on the constituency level do play a role in the allocation of compensatory seats.