8 | New Scientist | 9 November 2019
THE UK general election campaign
has begun, with voters having
to decide whether to support the
current Conservative government,
which wants to proceed with
leaving the European Union,
or try to replace it.
A pro-EU campaign group,
Best for Britain, has launched a
tactical voting guide designed to
help elect politicians who want to
change course on Brexit. The tool
has been criticised for giving what
some see as odd advice, but the
group says its choices are backed
by complex statistical modelling.
The Liberal Democrats are the
most anti-Brexit UK party, with a
policy of notifying the EU that the
country no longer wishes to leave.
However, it is also a minor party,
meaning its chances of winning
many of the 650 seats are seen as
slim. Despite this, Best for Britain
suggests a Lib Dem vote in 99 seats
where the party trailed the
incumbent by at least 25,000 votes
in the 2017 general election.
Best for Britain CEO Naomi
Smith says this advice isn’t due to
partisan bias, but rather the result
of how the group powered itscalculator. It used a relatively new
form of election modelling known
as MRP, short for multilevel
regression and post-stratification.
“MRP isn’t polling, that’s the key
thing that people probably don’t
quite understand,” says Smith.
Instead, it is a model that takes a
large initial polling sample (more
than 46,000 voters in this case)
and combines it with numerous
other factors (90,000 for thismodel) to make much more
granular predictions about the
behaviour of constituencies –
and even individuals.
The method saw a boost in
2017 when polling firm YouGov
released an experimental MRP
on the eve of the election, correctly
identifying the winning party in
93 per cent of seats. Chris Curtis
from YouGov says the principle
behind MRP is to model types
of voters, rather than relying on
traditional constituency polling.
For example, an MRP will model
the behaviour of a 24-year-oldwoman in the north-east of
England with a degree, then work
out how many such people there
are in different constituencies.
It then assesses other factors, such
as how marginal a seat is, as voters
in marginal seats are more likely
to switch parties than those in
safe seats. It also calculates
incumbency effects, which
particularly boost an MP’s
first election as the incumbent.
The techniques behind MRP
are decades old, but are largely
a new factor in politics. This is
partly because existing polling
techniques are becoming less
effective as it gets harder to
reach balanced samples, and also
because online polling decreases
the cost of the large-scale polls
needed to power the models.
There are limitations, of
course, not least that during an
election campaign, voters change
their minds. Smith says Best for
Britain is planning to update its
model closer to election day.
“MRP is still just like all polling,
telling us where the public is
right now,” says Curtis. “It is not
AL predicting the future.” ❚
EX
SEGRE/ALA
MYSTOCK^ PHOTONews UK general election
EnergyFracking banned as
UK parties compete
on green credentialsTHE UK government has brought
in a moratorium on fracking in
England and dropped measures to
speed the development of shale gas
wells, ringing the death knell for the
nascent industry. The sharp reversal
of support ends nearly a decade
of protests, court cases and minor
earthquakes without any energy
being produced.
The move comes after fracking
caused a magnitude-2.9 quakein August near Blackpool. It is the
largest so far after operations by
shale firm Cuadrilla in the past year.
A scientific analysis published
last week by the UK oil and gas
regulator concluded that bigger
future tremors couldn’t be ruled out,
which could cause unacceptable
“damage and disturbance”.
Although the moratorium applies
only to England, fracking is already
effectively banned in Scotland and
Wales. Opposition political parties
have pledged to ban the method of
extracting gas. The UK government
also ditched controversial planning
reforms to aid the industry.The decision follows the UK
spending watchdog saying last
month that fracking had cost
police forces and public bodies
£33 million, and that theindustry’s progress had been
slower than expected.
The opposition Labour party
accused the government of trying
to win over voters in next month’s
general election. It said that itwould ban fracking permanently.
Prime minister Boris Johnson
has said the environment will
be one of his top three domestic
priorities. Opposition to fracking
has long outstripped support in
official polling.
Although environmentalists
welcomed the fracking moratorium,
on the same day officials also gave
the green light for the country’s
first deep coal mine in decades,
near Whitehaven in Cumbria. ❚For more on climate change in the
UK election, see page 18Adam Vaughan2.
The magnitude of a fracking-related
earthquake in AugustA new way of modelling
is being used to offer
pro-Remain voting advicePollingJames BallRow over tactical voting site
Campaigners under fire for their statistical model for tactical voting