Ben RaueToday's blog post looks at how effectively each party turns its share of the vote into seats in the five most recent Tasmanian state elections. #politas https://www.tallyroom.com.au/55325
This chart shows there is a reasonably strong relationship between the number of quotas polled statewide and the number of seats won, but it does look like Labor can often win more seats off a given vote (or the same number of seats off a lower vote).
Usually parties win fewer seats than the raw number of quotas they poll (after all, there is one extra quota per seat, so a 25-seat parliament has almost 30 quotas of votes). Apart from 2014, Labor has generally overperformed, in particular in 2018 and 2021.
This chart shows the number of wins for a particular share of the vote in each electorate at each election. The most interesting part is the range between 1.5 and 2 quotas - this sometimes produces one win, sometimes two wins, and Labor tends to win off a lower vote than Liberal.
Part of the explanation is that having a relatively even spread of votes amongst your candidates will help you more than having the vote focused on one popular candidate. But I suspect preferences can also play a role.
So next up I looked at how many votes a party would gain in addition to its primary vote through the count, and average it out across all five electorates in each of the five elections. Labor does particularly well, in particular in 2018 and 2021.
You can also see it in this chart, which compares how many votes were lost by leakage out of the party ticket and how many were gained, throughout the distribution of preferences. Most of the cases where a party gained 0.2 or more of a quota were Labor.
