How closely did parties vote on bills in the last parliament?
By analysing party voting on final bill readings, we can see how the political parties differ when it came to legislation passed during the 49th New Zealand Parliament.
The closer two parties are on the plot, the more often they voted the same way in final bill readings. The distances between parties is calculated from their bill votes. The axes don’t have any special meaning.
Is there an explanation for the party clusters?
The National Party had a confidence and supply agreement with ACT, the Māori Party, and United Future in the last Parliament. Together these four parties formed the last Government.
Despite National and the Māori Party being in Government together, the Māori Party voted more closely with Labour in its voting on bills. National, Act, and United Future were relatively similar in their bill voting.
The Green Party voted differently from all other parties in its bill voting.
How was the party distances plot made?
The plot was created by a statistical analysis of final bill reading votes, using a technique called principal components analysis. The two principal components plotted above explain 83.2% of the variance in the way parties voted on final bill readings.
You can read a blog post for details of how to do the principal components analysis for yourself. The data is provided.