While some national opinion polls have shown Labor winning up to 21 seats and an average of national polls sits at around 16 seats, an analysis of about two dozen individual seat polls shows the party gaining far fewer. However, not all marginal seats have been polled individually.

Size of challenge

After allowing for redistributions which made three Liberal-held seats in NSW notionally Labor, the party needs to win 19 seats with a uniform national swing of 4.1 per cent, which would be about twice the average swing against a first-term government since 1972. The average swing in all federal elections since 1972 has been about 2.9 per cent, which also underlines the size of the Labor challenge at this election.

The analysis includes the first aggregation of the state voting figures from the three Fairfax-Ipsos opinion polls during the campaign to reduce the margin of error from the small state sample size and provide an insight into how different swings are playing out in different states.

The biggest swing of 10.6 per cent is occurring in WA and would give Labor six extra seats in the state on top of the existing three that it holds. Even after adjusting the figures for the possible margin of error in the expanded data Labor would win still Cowan, Hasluck, Burt and Swan.

Australian Financial Review Interactive Interactive graphic by Les Hewitt

But the other big swings of 4.1 per cent in Victoria and 4.2 per cent in South Australia will not provide substantial gains because the Coalition has few marginal seats in those states after Labor's strong performances at the recent elections in those states.

In comparison Labor is only getting swings of 2 per cent in NSW and 2.3 per cent in Queensland where there are relatively more marginal seats.


Smaller samples

The cumulative Ipsos state polling data shows there is no material difference in seat outcomes between 2013 preference distribution method and stated preference distribution even though there is sometimes difference between the preference distribution methods in the individual poll results.

Individual seat polls show much lower Labor gains than the national or state polling. However not all marginal seats have been polled, most individual seat polling is more dated and these polls sometimes involve smaller sample sizes. The seat betting numbers underline how the overall odds of the Coalition winning the election have tightened since the election was called.

There is an ongoing debate about whether betting odds or polls are a better gauge of election results.

All the bookies and pollsters correctly called the outcome of the 2013 election but the picture was more mixed for individual seats.

SportsBet had the correct favourite in 91 per cent of seats (137 of 150), the incorrect favourite in six per cent of seats (nine of 150) and no favourite for another four seats.

Pollsters correctly called between 71 per cent (Newspoll) and 77 per cent (JWS Research) of individual electorates that were surveyed.