One of the challenges about using a new system is understanding how it will impact the overall results. I have produced many simulations to show the impact of the Simple MMP on the composition of Parliament. I have also run simulations to predict the impact of other electoral systems on the overall outcome.
First, a word of caution about simulations. We are using past election data, but we know that if the system changes, people will change how they vote. In particular, a proportional system like Simple MMP will reduce the level of “strategic” voting. We can’t go back in time to find out, but we can be assured that next time, preferences will change.
Second, some of the simulations require some guessing, and therefore are subject to error. For example, in order simulate the Alternate Vote system, it was necessary to guess what voter’s second and third choices might be. This was done by using polling data from the end of the last election showing second choice party for the major parties. This is an estimate, but it is a reasonable estimate of how people might have behaved under different circumstances.
So with this in mind, here are some simulations for your consideration. Please feel free to do your own simulations as well.
Simulations of Simple MMP compared to historical outcomes
What would the 2015 election have looked like under Simple MMP? Click here
What would the 2011 election have looked like under Simple MMP? Click here
What would the 2008 election have looked like under Simple MMP? Click here
What would the 2006 election have looked like under Simple MMP? Click here
What would the 2004 election have looked like under Simple MMP? Click here
Simulations of 2015 election under various electoral systems
What would the 2015 election have looked like under Alternate Vote? Click here
What would the 2015 election have looked like if MPs were selected randomly from the list of candidates in each riding? Click here