A slightly different way to the simple division in Overview of looking at the range of choice within Proportional Representation (PR) systems is to differentiate systems by whether they use one or two 'tiers' to allocate seats, and by whether the lists are open, closed, or free (panachage). Countries that allocate seats only on one tier may do it by using national lists, as in Namibia and the Netherlands, or entirely by regional lists, as in Finland (see Finland: Candidate Choice and Party Proportionality) and Switzerland (see Switzerland). The Single Transferable Vote (STV) has almost always been used as a one-tier system (as in Ireland - see Ireland: The Archetypal Single Transferable Vote System).
Two-tier allocations may entail both national and regional lists, as in South Africa, regional lists only as in Denmark, a national PR list and a single-member district component as in Germany and New Zealand, or regional lists and a single-member district component as in Bolivia. Malta created a two-tier system out of its STV system in the mid-1980s by providing for some extra compensatory seats to be awarded to a party if it wins a majority of the votes but fewer seats than its rivals.
See: South Africa: Election Systems and Conflict Management,Germany: The Original Mixed Member Proportional System,New Zealand: A Westminster Democracy Switches to PR,Bolivia: Electoral Reform in Latin America and Malta: STV With Some Twists.
