I realized only today that I had misread the proposal for the Mixed-Member Proportional (MMP) system in the British Columbia Attorney General’s report on the options. [Or maybe not, after all: See Wilf’s comment.]
I had thought the compensation would play out only in regions, as is the case in Scotland. I based this on the phrase in the report that says, “the List PR seats are allocated on a regional basis rather than a province-wide basis.” However, somehow I missed the clear statement in the preceding paragraph of the report, where it says, “The overall share of seats each party holds in the Legislative Assembly is determined by the party’s share of the province-wide vote it receives.”
In other words, the regions would affect only which specific candidates are seated from the compensatory (“top-up”) lists, and thus the regional balance of each party’s caucus. They would not affect the number of such seats a party wins overall.
The provision also makes workable the possible open list, which is given as an option to be worked out post-referendum, but which the Premier has said he will ensure is chosen rather than a closed list. If the lists were province-wide, open lists would make for more cumbersome ballots and arguably excess choice (as well as failing to ensure regional balance in the assembly).
The details of how one balances province-wide proportionality with open regional lists are complex. It is the system in Bavaria, however, so it is not unproven.
I have corrected my two previous entries on this accordingly: