I am writing this late morning on 7 May 2021 in France. There was an MMP/AMS election yesterday in Scotland. And there are no results yet, it seems!
We are fortunate in New Zealand, that General Election results are processed quickly, and we seldom if ever need to go to bed on election night without having a very good idea of the result.
The Scottish system is very similar to the New Zealand one, but is called AMS, for A-additional M-member S-system. Named because they (like NZ) elect constituency MPs then ‘add’ list members to create a proportional result.
**********Edit 23/10/2022: The Scottish AMS system does not in fact produce a proortional result. There are normally overhangs in Scotland because the SNP is very dominant. And Scotland uses a ‘ modified d’ Hondt system’ to allocate seats. This seems to be cunningly designed to take list seats from small parties to make seats for SNP overhangs. In the process the result moves significantly away from proportionality. And they say they do not have overhangs.*******************
The Scottish system differs in that Scotland selects list MPs in eight regions, so that each region has it own more or less proportional result. There are no fixed thresholds, but because each region elects only about 16 MPs, there is an effective threshold of about 8%. Scotland also uses the d’ Hondt method for allocating seats, whidh reputedly is more favourable to larger parties that the StLague system in NZ.
It seems a problem of many description of MMP/AMS that they talk about having constituency elections then about ‘added’ list MPs to achieve proportionality.(***See edit above*****)
But as we know, it is the party votes that determine in MMP/AMS the overall makeup of parliament. So it is simpler to say that we use party votes to determine the overall number of seats in parliament for each party, and THEN fill those seats beginning with electorate/constituency winners, and taking the rest from party lists. (Noting that Scotland uses open party lists so that voters have a choice of list members, but voting papers are more complex).
Once you see it this way, the party votes are what you count first, because they take you straight to the overall result. By contrast the constituency and list results are of mainly local interest.
Two conclusions:
1. Descriptions of AMS/MMP should make more clear that it is party votes that almost solely determine the numbers seats in parliament for each party.
2. Once this is understood, it seems that Scotland could determine much more quickly the overall result of its AMS elections.
Comments relating to the New Zealand MMP threshold:
The use of several regions in Scotland makes for quite high effective thresholds. Many tiny parties have no hope of representation. The system might be made more proportional by having a fixed threshold and offering a second choice of party vote. That would allow every voter to vote for a party representated in parliament. The use of open lists in Scotland makes voting papers, and hence a second choice of party vote, more complicated than is proposed for NZ.