Coalition supporters, searching for reasons why a government that they think is just the bee’s knees should be headed for mammoth defeat, often seize on the “It’s time” factor: the idea that length of time in office, independent of other causes, provides a reason for people to vote against a government.

It’s a popular idea among commentators. Peter Brent, for example, argues that “young governments find re-election easy, while old ones find it increasingly difficult.” But is it true?

Well, let’s look at some numbers. By my count there have been 230 elections, state and federal, since the establishment of our two-party system in 1909. The following table summarises the results according to how long the government of the time had been in office.

Labor governments Non-Labor governments Total
Re-elected Defeated % Re-elected Defeated % Re-elected Defeated %
One term 25 15 63% 31 18 63% 56 33 63%
Two terms 16 5 76% 19 10 66% 35 15 70%
Three terms 10 5 67% 11 8 58% 21 13 62%
Four terms 5 3 63% 6 2 75% 11 5 69%
Five terms 3 2 60% 4 1 80% 7 3 70%
Six or more terms 9 3 75% 15 4 79% 24 7 77%
Total 68 33 67% 86 43 67% 154 76 67%

In other words, over the last century governments have about two chances in three of being re-elected, and that’s pretty much independent of which party they are and how long they’ve been in office. (I haven’t bothered with the figures here, but it also doesn’t vary much by
jurisdiction.)

But there is one interesting variation: the picture seems to have changed over time. Here are the figures again, this time divided into three roughly equal periods.

1909-1941 1942-1973 1973-2007
Re-elected Defeated % Re-elected Defeated % Re-elected Defeated %
One term 22 22 50% 10 7 59% 24 4 86%
Two terms 12 5 71% 9 2 82% 14 8 64%
Three terms 4 6 40% 11 1 92% 6 6 50%
Four terms 3 0 100% 7 2 78% 1 3 25%
Five or more terms 0 2 0% 22 5 81% 9 3 75%
Total 41 35 54% 59 17 78% 54 24 69%

So the electorate was less tolerant of governments in the early period, became much more so in the mid-twentieth century, and a bit less tolerant again in recent years. But in the recent period the re-election rate for first-term governments has shot right up, while the others have all dropped.

In the last few decades it seems true to say that second-term governments have a tougher task than first-term ones, and third- and fourth-term governments tougher again. Beyond that, however, the picture is murkier, and the sample sizes are too small to be confident about drawing conclusions.

It looks as if recent history gives some support to the “It’s time” theory, but it is probably still best to treat it as a conjecture rather than an established truth.