The Mathematics of the
General Election
Dr Justin Greaves
Department of Politics
University of Warwick
Outline of this talk
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The basics (background and context)
What is a ‘swing’?
What is a ‘hung parliament’?
The electoral system
Opinion polls
The national debt (perhaps the main
election issue?)
So, what are the basics?
• More than 45 million people aged 18 or
above vote for a new Member of
Parliament (MP) for the area in which
they live (Constituency)
• Elections must be held at least every
five years in Britain – up to PM to
choose the date
• Traditionally held on a Thursday
Why a Thursday?
• One theory about its
origins is that people
were not paid until
Fridays and so
holding polls on
Thursdays ensured
they were not too
drunk to vote
Two controversial issues
1. Should the voting
age be reduced to
16?
2. Should we
introduce
compulsory voting
(as in Australia)?
The three main parties
The three party leaders
The TV debates
• This is the first
election in the UK
where there have
been TV debates
between the three
party leaders
• Here is a clip from
the 2nd debate
Too much celebrity?
• Is it becoming too
much like the X
Factor or Britain’s
Got Talent?
• Leaders judged on
how good they look
on TV?
So now onto the maths ....
What is a ‘swing’?
• Swing is a tool which
helps explain how
elections are won and
lost
• In simple terms it is a
way of measuring
how the public's
support of political
parties changes from
one election to the
next
The calculation
• Step 1. Add the rise in one party's share
in the vote to the fall in the second
party's share of the vote.
• Step 2. Divide your figure by two. The
resulting figure is the swing.
An example
• In the 2005 General Election the Labour
Party had a lead of 3% over the
Conservative Party
• Let’s assume that in Thursday’s
election, the result is a Con lead of 4%
over Labour
• Exercise: calculate the swing
The answer
• This is a swing of
3.5% (3+4/2).
What to look out for
• 1.6% swing against Labour: Labour lose
their overall majority
• 4.3% swing against Labour: The
Conservatives become the largest party.
They would still not have an overall
majority.
• 6.9% swing against Labour: The
Conservatives gain an overall majority and
therefore form the next government
(but will a UNS operate?)
What is a ‘hung parliament’?
• If one party has an
absolute majority it
means that it has
more seats than all
the other parties put
together (326+)
• If no party has such a majority then
there is a hung parliament
• The smaller parties can then join forces
to out-vote the government
• This makes it difficult to pass laws
• There is a good
chance of a hung
parliament resulting
from this election
• The last time it
happened was in
February 1974
Options in a hung parliament
• Formal coalition (alliance with another
party)
• Confidence and supply
• Minority government
• If none of these options work there
would have to be another election
Why is it so rare?
• Hung Parliaments and coalitions
happen a lot in other countries
• So why are they so rare in the UK?
• This is mainly a result of our electoral
system
Proportional Representation
• Many countries have a proportional
electoral system (eg: under PR if a party
wins 30% of the votes, it will win approx
30% of the seats)
• It is rare for any one party to get over
50% of the vote
• Therefore, in these countries parties will
have to work together
First past the post
• Britain has a first past the post electoral
system
• Therefore, 650 constituencies
• In each one, the candidate who gets the
most votes wins (even if it is less than
50%)
• EG: if the winner gets 36% of the vote
they still take the seat
• It is like a horse race
• The winner of the
race is the first to
pass a particular
point on the track
Strange results
• FPP can throw up strange results:
1.A party with 35/40% support can get
well over 50% of the seats
2.The party that wins most votes may not
win most seats (eg: 1974)
3.The Lib Dems could come first in vote
share and third in seats
Opinion polls
• You may have seen opinion polls in the
media
• These may only interview 1000 people
out of the whole population of Britain
• If the sample is ‘representative’ these
polls should be accurate
• Polls usually have a
margin of error of +
or – 3%
• 19 times out of 20 a
poll should fall
between this margin
of error
Think, pair, share
• What could cause
an opinion poll to be
biased or skewed in
some way?
National debt and borrowing
• One of the biggest
election issue is the
amount of money the
government is
borrowing (and
Britain’s national debt)
• Due to the recession
the government had
to borrow a lot of
money
• One reason was to
rescue the banks
• Another was to pay
benefits to those
who became
unemployed
• And if people are
out of work the
government also
loses tax revenue
Party Policy
• The Labour Party plans to reduce the
amount we borrow by 50% over four
years (starting in 2011)
• The Conservative Party say this is not
enough. They want to go cut faster and
deeper
Debt statistics
• Borrowing of £163
billion last year
• The government
forecasts that debt
will soar to £1.1
trillion by 2011
Debt statistics (2)
• We owe £14,480 for
every man, woman
and child
• That's more than
£31,254 for every
person in employment
• Every household will
pay £1,898 this year,
just to cover the
interest
Thank you for listening