
The perils of MMP
"Mixed-member proportional representation (MMP) is the type of mixed electoral system that is associated with Germany and New Zealand. Its defining feature is called seat linkage compensation, which in theory offers ‘the best of both worlds’. Mixed proportional systems aim to provide both proportionality and still keep representatives elected locally in single-member districts (SMDs). This is in contrast to mixed majoritarian systems, where the aggregate outcomes of the SMD seats (which may be highly disproportional) are not compensated for. It is, however, far from a perfect system, even if it may be a normatively desirable amalgamation of PR and localized winner-take-all methods. In fact, the most common version of MMP is highly vulnerable to strategic abuse of the compensatory subsystem, which has led to MMP (and similar systems) failing in more countries than where they succeeded.
In this article, I will not only show how MMP has failed in different countries, but also offer some explanation on why it didn’t fail in others, as well as consider some proposed solutions to make such systems less vulnerable. I also present my own solution to make MMP more robust while not sacrificing its main features, which I have been circulating in election reform circles for a while now."