The Gallagher Index is a basic measure of disproportionality of electoral outcomes, and therefore of their fairness. As someone interested in the fairness of our electoral system, I thought I'd calculate it for the 2011 election, based on the preliminary results:
| Party | % Vote | Seats | % seats | Difference | Diff |
| National | 47.99 | 60 | 49.59 | 1.60 | 2.55 |
| Labour | 27.13 | 34 | 28.10 | 0.97 | 0.94 |
| Green | 10.62 | 13 | 10.74 | 0.12 | 0.02 |
| NZ First | 6.81 | 8 | 6.61 | -0.20 | 0.04 |
| Māori Party | 1.35 | 3 | 2.48 | 1.13 | 1.28 |
| ACT | 1.07 | 1 | 0.83 | -0.24 | 0.06 |
| Mana | 1 | 1.00 | 0.83 | -0.17 | 0.03 |
| United Future | 0.61 | 1 | 0.83 | 0.22 | 0.05 |
| Conservative | 2.76 | 0 | 0.00 | -2.76 | 7.62 |
| ALCP | 0.48 | 0 | 0.00 | -0.48 | 0.23 |
| Democrats for Social Credit | 0.07 | 0 | 0.00 | -0.07 | 0.00 |
| Libertarianz | 0.07 | 0 | 0.00 | -0.07 | 0.00 |
| Alliance | 0.05 | 0 | 0.00 | -0.05 | 0.00 |
| Total | 12.82 | ||||
| Gallagher Index | 2.53 |
(All figures rounded to 2 d.p.)
This is slightly below the average for NZ elections under MMP (time series here). 2008 had a Gallagher Index of 3.84; 2005 had 1.13 (FPP's average since 1946 was 11.10, with the last two FPP elections being 17.24 and 18.19 - which explains why people wanted MMP so badly).
2.53 is low internationally, but we can clearly do better. And the obvious way of doing that is by removing the threshold and giving people the freedom to vote how they please.