Power Indices

Once more information comes out about the budget, expect more posting here. Really reassured that the people responsible for the budget are acting like grownups and working to get together a budget. This is how minority governments are supposed to work - you cooperate with enough other people to have the backing of a majority of votes, or your government falls. I'm glad the Conservatives have finally figured this out, and look forward to seeing more Liberal policy and priorities making it into future bills and budgets. (Dare to dream, right?)

Anyway, now that we are in our third minority government in a row (and it looks likely that we will see more of the same in the future) there is a decent amount of data to look at how voting power of the parties changes (and doesn't change) with seat distributions. Here I'm using the Penrose-Banzhaf index to determine the voting power index for each party, which represents the proportion of all possible successful votes which require the support of a given party (or the proportion of all possible coalitions which require the support of a given country, if you like).

38th Parliament
This is the last time the good guys were in charge. Upon dissolution, Parliament looked something like this:
The power indices show how tight this Parliament was - the purple slices on the power-index graph represent single independent MPs. In this configuration, the Liberals required either the Conservatives, the Bloc, or the NDP and three independent MPs to maintain a majority; conversely, a coalition of the Conservatives, Bloc, and any three independent MPs would have constituted a majority. This unusually close balance of power led to lots of drama and excitement, including Conservative Belinda Stronach crossing the floor to the Liberals, and the Conservatives (allegedly? probably?) attempting to bribe independent Cadman to support them.

39th Parliament
This is where Harper becomes Prime Minister and the Liberals are led by Dion. Upon dissolution, Parliament looked something like this:
Here, the power index shows that the possible combinations were much less interesting, even though the Conservative share of seats was lower than the Liberals' in the previous Parliament; since the Conservatives could continue to rule in combination with any one party, their power index was much higher, as their situation was far more stable.

40th Parliament
This is how things stand as of posting:
Note that the power indices are exactly the same as last time, reflecting the unchanged ability of the Conservative party to pass any bill with the support of at least one other party.

The power indices allow for several interesting inferences about the function of minority governments in the last five years:

1. Independent MPs sometimes make a difference. In a minority government, the ability to lure independent MPs (and disaffected members of other parties) can be crucial to governmental survival.
2. The two parties which have seen an increase in power index under the two successive Conservative minority governments are the Conservatives and the NDP. The Liberals have (obviously) lost the most power.
3. The last election did not change the balance of power. While the decline in Liberal representation does mean less Liberal voices in the House of Commons and less incumbency advantage and less familiar faces for the next Liberal government, the election did not increase or decrease the ability of the Liberals (or any other party) to form government.