Frequently Asked Questions
The site tries to help understand the General Election system by
translating the support levels for each party into actual seats.
The aim is to de-mystify a process which is already well-understood
by party insiders, and to make it accessible to anyone
who is interested. The site tries to make the least inaccurate
prediction possible and is independent of any other organisation.
No. The predictions are based on the law of averages, but any
individual seat could be wrongly predicted.
Also if the opinion polls are wrong, that will cause more seats
to go wrong. Usually about 50 seats
are incorrect. Look at the track record
for details of elections since 1992, or see all the
errors in 2001.
Yes. The purpose of the site is not to tell people how to vote
but to predict the election outcome given that people have
told the opinion pollsters how they intend to vote. The site lets
voters in a particular seat estimate the local strength of
the parties from national trends. The ultimate
decision in that seat is determined by those voters and no-one else.
Local factors can be very important. These can include
a particularly popular (or unpopular) incumbent, a recent
by-election, an important local issue, and so on.
Unfortunately they cannot be included, as
predictions are driven by national levels of support, as measured
by national opinion polls. On average local factors must balance
out, but the prediction in a particular seat may be incorrect.
Yes, in the user-defined prediction you can now enter tactical voting
parameters. The most important of these describes how Liberal Democrat
supporters will behave in seats where the Lib Dems are very likely to
be in third place, but Labour and the Conservatives are close together.
See Tactical Voting model.
Scotland has four major parties, so needs special handling. So the model
allows all four parties to move dynamically, as measured by the
Scottish opinion polls. The regular Scottish poll was published by
The Herald until December 2003. Since then, there have only been
occasional Scottish opinion polls. The prediction for Scottish seats
has been relatively static since then and can only be updated when new Scottish
opinion polls are published. There were only two polls conducted during 2004,
but there have been more recently. They are
shown on the scottish opinion poll page.
Minor parties are treated collectively in the prediction. Their
share of the vote is allowed to move up and down at the expense
of the other parties. However it is not possible to separate
the small parties from each other, or to allow for regional variation.
This may be a problem if UKIP does well in particular areas
and takes votes disproportionally from the other parties (such as
the Conservatives).
The data shown is the snapshot provided by the May 2005 General
Election. To keep the consistency of the dataset, it is deliberately
not updated to reflect by-elections or changes of party affiliation.
This is necessary so that we can predict the next election on
the basis of the change in support since May 2005. This would make
less sense if the base data were measured at different times.
Also, by-elections are a famously poor predictor of general elections.
Uniform National Swing (UNS) is not foolproof, but it is simple and intuitive.
It has been modified to keep shares of votes positive
(see model details). Given that the data available is
only national support figures, it seems the best available option. Our
track record of UNS predictions is available.
The model is basically Uniform National Swing (UNS), with an adaptation to
keep each party's share of the vote positive. The full details are here.
About once or twice a month, as national opinion polls are published. You can
get email notification of updates by joining our mailing list.
No. All the polls used are opinion polls conducted by the major
market research companies, and published in the national press. Generally, we
only use those polls which come out as a monthly series. This ensures that
each pollster is represented equally in the rolling average.
History of polls since 2001.
Due to the lack of Wales-specific polls, it is necessary to keep
the PC share of the vote fixed since 2005. This is inaccurate, but
should not affect too many seats. The main exceptions are probably
Llanelli and
Ynys Mon.
Please let us know if you see any Wales-wide opinion poll.
This needs regional opinion polls to provide the input data. These have been
available for Scotland (though not since 2004), but are not generally
published. During the election campaign there may be a large poll conducted
by the Press Association which contains regional swing information.
Absolutely. The Liberal Democrats vote is modelled to allow it to go up
or down at the expense of the other two major parties (and the minor parties).
The model is fully multi-party and is not a simplistic one-dimensional swing
model.
The model used has elements of a Markov transitional model (see
model details), but is basically a modifed
Uniform National Swing model. Markov models break down the current levels
of support for each party according to how that person voted in the
previous election. That is, it shows for those who voted (say) Labour in 2005,
how many still back Labour, and how many back each of the other parties.
The model is interesting conceptually, but it has too many parameters to
be calibratated using the published national opinion polls.
The regions used are unique to this site and are designed to break the
country down into 20 regions, each of which is (relatively) homogeneous
electorally. Our regions are made up of entire counties or unitary local
authority areas, but do not correspond to any official definition of a "region".
As an additional quirk, our region "South London" contains three west London
boroughs which lie above the Thames, in order to keep the two halves of London equal.
They are Ealing, Hillingdon and Hounslow. Full
region composition.
Stranger yet, the seat of Ealing
Acton and Shepherd's Bush is split between the boroughs of Ealing (six wards) and
Hammersmith & Fulham (five wards). This leads to the seat being classified as
"South London" by a majority of one ward.
The Battlemap is less powerful than the full multi-party model as it is only
two-dimensional. This means that only the three major parties can move, and the minor
parties are assumed to stay fixed. You can adjust for this through
power use of the Battlemap. Or it is easier to
use the multi-party model to make your own predictions.
Either because you have spotted it before we have, or because it is not
a regular monthly poll from the series used in the rolling average.
If you do see a poll we haven't used yet (including any for Scotland or Wales)
please email us the details.
No.
Return to top of this page or home page.