Evaluative Satisfaction System (Pacifica)

The Evaluative Satisfaction System (ESS) is a mixed electoral system under which representatives in a multi-member body are elected on two tiers via a single round of evaluative voting. Representatives are first chosen in single- or multi-seat constituencies as the lower tier by using a majority vote; the overall composition of the body is then made to approach proportionality on the upper tier using a best-loser algorithm.

ESS is a semi-proportional electoral system, since parties might win more constituency seats in the lower tier 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 on the upper tier possible again. This issue typically affects elections where there are too few upper-tier seats in comparison to constituency seats.

The system was first developed for and used in the 2012 Tepertopian Assembly election with the intention to incentivize voting honestly rather than strategically. It has drawn both praise and criticism: Supporters often laud that its straightforward ballot layout makes casting one's vote accessible and ballots hard to spoil unintentionally, as well as that the multiple different tallies from each ballot make the election relatively resistent to strategic voting; critics however complain that this very fact also renders elections intransparent by making it hard for voters to precisely see how their vote will influence ‒ and, even after polls close, how it actually did affect ‒ the results.

Procedure

An ESS Ballot for the 2021 Tepertopian Assembly election

Under ESS, each voter casts a single evaluative voting ballot: Any number of candidates they approve or disapprove of may be marked, with the option to avoid marking a candidate altogether to express indifference. Candidates may be linked to a party list or stand as independents.

Lower tier

In the first step of the election procedure, representatives are determined on the constituency level as the lower-tier seats. Each constituency elects at least one 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, having just a single constituency is equally viable, but the number of candidates standing can grow quite quickly with an increasing amount of constituency seats, thus limiting the practicability of single-constituency elections.

The exact method used to elect representatives is satisfaction approval voting (adapted to evaluative voting ballots): The approvals and disapprovals on each ballot are first assigned a specific weight, equal to 1 ÷ (amount of approvals/disapprovals given). This effectively means that a voter divides a single approval and a single disapproval equally between all respectively approved and disapproved candidates. For each candidate, all thusly weighted approvals and disapprovals are summed, with the latter then subtracted from the former to find each candidate's constituency score. The candidate(s) with the highest constituency scores win the constituency's seats.

This way of selecting constituency winners requires the various parties to carefully choose how many candidates it wants to field in each constituency ‒ too many, and voters may divide their approvals between party candidates so much that they fall behind competitors; too few, and there might not be any more candidates of the party to fill any upper-tier seats it may be awarded.

Upper tier

The second step, electing the upper-tier compensatory seats, works similarly. First, the ballots are re-counted, again dividing the approvals like before but completely ignoring independent candidates and approvals that went towards them; the disapprovals however are not divided anymore. As their vote share for the proportional distribution, parties are then assigned the sum of the newly calculated weighted approvals of all its candidates (excluding the disapprovals). The order of the candidates on the party lists is then determined by the number of disapprovals they respectively received, with the candidate disapproved by the lowest percentage of their constituents leading. Finally, the compensatory seats are handed out iteratively: Until all seats are filled, the most-underrepresented party (highest difference between vote share and current total share of seats won by its candidates ‒ including lower-tier seats) sees the candidate highest on its list elected.

Like the lower tier, upper tier seats may be awarded in "constituencies" as well, with each upper-constituency consisting of a number of lower-constituencies. In this case, the above method is conducted separately in each upper-constituency.

Upper tier seats may also be restricted to parties meeting specific eligibility criteria, e.g. surpassing an electoral threshold or having a certain number of candidates elected on the lower tier. Should this be the case, approvals towards candidates of ineligible parties are completely removed from the election in addition to those towards independent candidates.

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 = ✗

Lower tier

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

Candidate	Weighted Approvals	Weighted Disapprovals	Constituency Score
. A	4 * 0.5	0	+2
. B	4 * 0.5	3 * 1 + 2 * 0.5	-2
. C	3 * 0.5	4 * 1 + 1 * 1	-3.5
. D	3 * 0.5 + 1 * 0.5	2 * 0.5	+1
. E	2 * 1 + 1 * 0.5	0	+2.5

As candidates A and E have the highest constituency scores, they are elected as representatives on the lower tier.

Upper tier

For the purposes of demonstration, Examplington qualifies all parties for compensatory seats without any restrictions. The independent E however does not play any role for the second step, since only party-affiliated candidates are considered ‒ the two voters whose only positive approval went towards E are consequently completely removed from second step calculations. Consequently, the compensatory scores und according party vote shares for each of the ballots divides as such:

Ballots Candidate	4×	3×	2×	1×	Compensatory Score	Party Score	Vote Share
. A	0.5				2	4	50%
. B	0.5				2
. C		0.5			1.5	4	50%
. D		0.5		1	2.5
Total:						8	100%

In terms of party score, 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 vote shares 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	1/3 = 33%	50%	12%
Yellow	0	0/3 = 0%	50%	50%

As the yellow party is more under-represented than the green party, it is awarded the seat. Within 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 for a total disapproval rate of 50%, and candidate D received 2 for a rate of 20%. 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 lower tier than it would be entitled to in the upper: If a party would be entitled to 50% of the seats, but its competitor already won a total of 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 voting), 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 rate, whereas MMP often features a closed 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. Strictly speaking, ESS could be considered a variant of the AMS adapted to the use of Evaluative 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 awarded 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 totality of the seats to be elected for its proportional component; accordingly, the seats a party has won on the constituency level do play a role in the allocation of compensatory ("top-up") seats.