2025 Senate Notes Part Two

This is part two of a detailed review that I write after each Senate election.  See part one for a general introduction and coverage of proportionality, winning vote shares, preferencing impacts and the curse of Inclusive Gregory.  This part covers Senate 2PP, How to Vote cards, just-voting-1, exhaust, informals, below the lines, and poor performances.

Senate 2PP

Senate 2PP is useful especially for looking at personal votes in the House of Representatives - how an MP does in Reps 2PP relative to their party's Senate 2PP in similar seats may give an insight into how popular they are.  I determine Senate 2PP by adding the above-the-line two-party preferred vote between the two major parties to the below-the-line two-candidate preferred vote between the lead candidates of the two parties.  It has only been a useful measure to calculate since Group Ticket Voting was abolished.

Because preferences in the Senate are semi-optional, Senate 2PP can tend to amplify a clear winner because of exhausted votes, and it also tends to favour Labor in that the 2PP exhaust rate off Greens votes is very low compared to other parties.  The previous election Senate 2PPs were: 2016 50.08 to Labor,  2019 52.66 to Coalition and 2022 52.93 to ALP.  At this election Labor won the Senate 2PP 56.76-43.24, a 3.83% swing.

NSW 56.54 (+5.34)
Vic 57.13 (+1.21)
Qld 52.12 (+4.55)
WA 58.16 (+0.96)
SA 60.42 (+6.67)
Tas 64.00 (+8.96)
ACT 72.34 (+6.00)
NT 54.97 (+2.16)

Senate 2PP doesn't gauge the performance of other parties; thus Labor won three seats in Victoria with a lower 2PP than WA where it missed out.

Senate Reform Performance Review 2019

The results of this year's half-Senate election are all in so it is time to observe how our new Senate system performed at its first half-Senate test.  Australian Senate voting was reformed in the leadup to the 2016 election to abolish Group Ticket voting and the preference-harvesting exploits it had become prone to, and give voters more flexibility in directing their own preferences either above or below the line.  In the leadup to that election, many false predictions about Senate reform were made and were then discredited by the results.  I reviewed how the new system went back then: Part 1, Part 2.  Some of the predictions that were made by opponents of Senate reform concerned the results of half-Senate elections specifically, so now we've had one, it's a good time to check in on those, as well as on how this election compared to 2019.  One unexpected issue with the new system has surfaced, concerning above the line boxes for non-party groups, but it is one that should be easily fixed.

Senate Reform Performance Review Part 1

The results of the Senate election are all in and so it is timely to review how the new Senate system performed in full detail.  No system should be expected to perform flawlessly on its first attempt.  However, the new system has generally exceeded the expectations of its most ardent supporters (save any who supported it for the wrong reasons) and made its opponents' pre-election arguments look very silly indeed.

Two major models of reform were canvassed in the Senate reform debate that ran through the last term of parliament.  The original JSCEM model released in 2014 allowed for fully optional preferencing above the line with semi-optional preferencing (six squares for a half-Senate election, twelve for a double dissolution) below the line.  The revised model released in 2016 initially allowed for semi-optional preferencing (1-6) above the line, but essentially maintained compulsory full preferencing if voting below the line.  After many complaints from the psephosphere (and I especially give credit to Michael Maley and Antony Green here) the final version as amended allowed semi-optional preferencing (1-12) below the line as well.  This change, in the end, allowed Tasmanian voters to overturn the contentious demotion of a sitting high-profile Senator.

Tasmania Senate 2016 Button Press And Analysis

Result

Order 1 Abetz (Lib) 2 Urquhart (ALP) 3 Whish-Wilson (Green) 4 Lambie (JLN) 5 Parry (Lib) 6 Polley (ALP) 7 Duniam (Lib) 8 Brown (ALP) 9 Bushby (Lib) 10 Singh (ALP) 11 Bilyk (ALP) 12 McKim (Green) 
Colbeck (Lib) was passed by McKim and McCulloch and excluded
5 Labor 4 Liberal 2 Green 1 Lambie

I would like to thank all the AEC staff in Hobart for all their help with information on the count and congratulate them on their efficient and punctual delivery of the Tasmanian outcomes.