The output indicators for Italy 2022: Yes, MMM in a smaller assembly really mattered

In the pre-election planting I pointed out how much more disproportional Italy’s electoral system would be, given the substantial reduction in assembly size. The current allocation rules and balance between single-seat districts and list-PR seats remained unchanged since 2018, but the assembly size was cut from 630 to 400. (Here I will be referring only to the Chamber of Deputies.) The system is mixed-member majoritarian (MMM).

Assuming I calculated things correctly–and I think I did, but the party vs. bloc calculations can be a little confusing, so caveats apply–here is how the change mattered.

I will report effective number of seat-winning parties (NS), effective number of vote-earning parties (NV), and deviation from proportionality (D2, the Gallagher index also known as the Least Squares Index). I will report both by individual party and by pre-electoral bloc. I believe that for an electoral system like this, the bloc figures are more meaningful, but here you have both and can decide which one works for your analytic purposes.

2018 Party2018 Bloc2022 Party2022 Bloc
D2 (%)3.985.027.3011.74

The change is pretty dramatic. Taking that last line first–disproportionality–we see an increase at the bloc level from around five percent to nearly twelve percent. The 2018 bloc-level figure is a level just below what we might see in a moderately proportional system like Estonia (5.3% in 2019) or Spain (5.37% in 2016) or Luxembourg (5.20% in 2013). The 2022 bloc-level figure is closer to what we might find with a majoritarian system, such as Canada (11.3% in 1988) or the UK (11.8% in 2019) or to take a “brotherly” MMM example, Japan (11.5% in 2000). Thus the increase is quite consistent with how I characterized the system in the previous post, as having changed from an effective seat product just over 900 (consistent with moderate PR) to one of 650 (the same as the value for the UK) solely due to assembly-size reduction.

The effective number of seat-winning blocs is certainly in the ballpark of expectations under a majoritarian system, with 2.90 in 2018 and a drop to 2.40 in 2022 when the assembly size reduction makes it even more majoritarian. The reduction in 2022 occurs in spite of a slightly increased fragmentation of the vote, even at the bloc level (from 3.36 to 3.44). That is, of course, why the disproportionality is so high in 2022.

The bottom line result is that the center-right bloc obtained 59.3% of the seats on 43.8% of votes–a classic majoritarian outcome. In 2018, for comparison, it had 42.1% of the seats on 37.0% of the votes. Its votes grew by 6.8 percentage points, but its seats by 17.2. Some of that is due to the bigger gap between the top two two blocs this time around, which in turn was a product of the center-left’s less complete alliance formation, but a lot of it is the lower number of single-seat districts resulting from the cut in the Chamber size.

Based on the seat product model, by which we expect NS=(MS)1/6, and using the numbers reported earlier for effective seat product, we should expect the 2018 system to yield NS=3.12 and the 2022 system to yield 2.94 (based on effective seat products of 920 and 650, respectively). These are “politics blind” expectations, based solely on the systems’ fundamental design features–district magnitude of the basic tier and the sizes of the tiers that comprise the assembly. We can see that in both elections the actual outcome by blocs was a little less fragmented than these expected values, but not to any extraordinary degree. The calculation of effective seat product for these complex systems gets their impact on the assembly party system about right.

As I mentioned, I do think these indicators are more meaningful when calculated on party level for a system like this. The parties within a bloc coordinate nominations in the single-seat districts, and the contest over who will form the post-election government takes place between blocs. Thus the blocs are the meaningful units. On the other hand, nothing commits the parties within a bloc to continuing to work together, and they agree that the votes for list will determine which one gets the prime ministerial post if the bloc wins a majority. The parties thus remain relevant and competitive actors, too. The outcome at party level was a little less “blocky” overall this time, with more parties gaining significant vote and seat shares despite being outside a bloc.1 But even at the party level, what is likely to matter most–at least in the short run–is that the largest party within the largest bloc has a majority of its bloc’s seats (119 of 237 for the Brothers), despite only 26% of the overall vote for parties.2

All in all, the the key take-home outcome is that the MMM system strongly rewarded the parties that had coalesced to form the biggest bloc, and the largest party within that bloc. That is just as we would expect MMM to do, particularly with such a reduction in assembly size.


  1. Five Star was in this category both elections. In 2018 it won 32.7% of votes and 36% of seats. This time it dropped to 15.4% of votes and 13% of seats. In addition, Action–Italia Viva in this election had 7.8% of votes and 5.3% of seats. More to the point, the three biggest blocs (counting Five Star as one of the “blocs”) had 92.5% of the votes in 2018 but just 85.4% in 2022.
  2. Quite different from 2018 when the League had just 47% of its bloc’s seats–which were in any case not a majority of the Chamber. The League’s party vote in 2018 was 17.4%.

7 thoughts on “The output indicators for Italy 2022: Yes, MMM in a smaller assembly really mattered

  1. I would caution that in Italy proper minus Valle d’Aosta and Trentino-Alto Adige/Südtirol, the right-wing coalition won nearly identical SMD seat shares in both houses – 83.8% in the Chamber of Deputies and 83.6% in the Senate – with identical 44% shares of the vote in both cases, even though the number of SMD seats in the Senate (67) was significantly smaller than in the Chamber (142). Also, note that for the 2022 election the voting age for Senate elections was lowered to 18.

    In addition, it’s worth noting that under the old bonus-adjusted PR system, the right-wing coalition would have won 216 Chamber seats in Italy proper.


    • I had not done a breakdown by list vs. nominal. Over 80% is impressive dominance! And much higher than one could reasonably expect without knowing anything about regional distribution of the vote or other “political” factors. Obviously, it means they did well across the regions.

      This performance is no doubt a big part of why the effective number of seat-winning parties is even lower than I indicate as my a priori expectation.


      • With 67 single-seat districts, a politics-blind expectation would be 59% of seats (about 40), and with 142 it would be 53.8% (79). So they over-performed by about 16 and 44 seats, respectively. Had they won only this “expectation” but done just as well in the list component they would have ended up with around 48% of seats, instead of 59%. A leading party (bloc) with 48% of seats is consistent with Ns around 2.6, or considerably closer to my seat-product expectation of 2.94 (for the Chamber).


        • Notional 2022 election results in seven regions for the Chamber of Deputies under the old SMC configuration in place before the constitutionally mandated seat reduction suggest that said reduction made little difference in their distribution among coalitions and single parties.

          Except in the largest cities, parliamentary SMC boundaries in Italy run along municipal lines, and in most cases notional election results under the old boundaries can be obtained by adding up municipal-level figures.

          In the regions of Trentino-Alto Adige/Südtirol, Veneto, Friuli-Venezia Giulia, Emilia-Romagna, Toscana, Umbria and Marche, located in north-eastern and central Italy, the center-right coalition won 44.8% of the Chamber vote and 37 of 45 SMC seats (82.2%), while the center-left coalition won six seats (13.3%) with 29.6%; the South Tyrol People’s Party (SVP) won the remaining two seats (4.4%) with 1.3%, while M5S and A-IV won no SMC seats, even though they polled 9% and 8.4%, respectively.

          However, had the election in those regions been carried out under the old SMC boundaries, and had voters cast their ballots in the same manner, the center-right coalition would have secured 56 of 70 seats (80%), while the center-left coalition would have obtained 12 (17.1%), with SVP winning the remaining two seats (2.9%).

          The small variation in the SMC seat outcome was due to the fact that the center-right coalition won sweeping victories in Veneto, Friuli-Venezia Giulia, Umbria and Marche, capturing all SMC seats in each of those regions under either scenario, in nearly every case by landslide margins; in fact, in Veneto the right-wing alliance prevailed in all of the region’s 563 municipalities, and no SMC configuration based on whole municipalities could have produced even one seat with a center-left majority. At any rate, in the cited regions the seat reduction made no difference whatsoever in the election outcome.

          However, in the regions of Emilia-Romagna and Toscana, where the center-right coalition prevailed by much narrower margins, the reduction of seats worked to its advantage, as it obtained 14 of 20 SMC seats (70%), but would have won 19 of 31 (61.3%) under the old seat boundaries. This was so because it secured three seats – Modena, Ravenna and Livorno – by narrow margins over the center-left coalition, which would have been notionally overturned had the election been carried out under the old boundaries. Nevertheless, in last month’s election cases like these were comparatively few in number throughout Italy.


  2. I’d be curious on your thoughts on the Quebec results when they come out today. There’s a possibility the second place party in terms of votes wins 0 seats.


    • I have now obtained preliminary notional 2022 Chamber of Deputies election results for the old 231 single-member colleges used in the 2018 election (excluding Valle d’Aosta), of which the center-right coalition would have obtained 185 (80.1%) to 25 for the center-left coalition (10.8%), 18 for M5S (7.8%), 2 for SVP (0.9%), 1 for ScN (0.4%) and none for A-IV. After the proportional distribution of 386 list seats, the center-right coalition would have secured 365 mandates (59.2%) in Italy proper minus Valle d’Aosta, to 132 for the center-left coalition (21.4%), 83 for M5S (13.5%), 32 for A-IV (5.2%), 4 for SVP (0.6%) and 1 for ScN (0.2%).

      By comparison, in the actual outcome the center-right coalition won 235 of 391 Chamber seats in Italy proper (60.1%), including 121 of 146 single-member college seats (82.9%).

      Although the four major contenders had candidates in every Chamber SMC, vast swathes of Italy were non-competitive due to the overwhelming dominance of the right-wing alliance outside the major urban centers. In particular, in the northern regions of Piemonte, Lombardia, Veneto, Friuli-Venezia Giulia and Liguaria the center-right coalition won all 45 SMC seats outside Turin, Milan and Genoa with 52.7% of the vote – the center-left coalition placed a distant second with 24.9% – and would have won as well all 71 mandates in those areas under the old seat configuration. In turn, this limited the impact of the reduction of parliamentary seats. Moreover, the percentage distribution of 386 list seats – initially allocated on a nationwide basis – would have scarcely changed relative to the actual outcome.

      Liked by 1 person

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