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Last Updated: Thursday, 17 February, 2005, 09:42 GMT
The axle of evil?
A 4x4

On More or Less this week we took a brief look at the evidence against 4x4s on pollution and other issues. The axle of evil as one critic says.

But what do the statistics show?

On the question of safety, much information about safety comes from American studies which include larger 4x4s (or SUVs) than we tend to see in Britain.

MORE OR LESS
BBC Radio 4's More or Less was broadcast on Thursday, 17 February at 1500 GMT

It also includes pick up trucks and a larger proportion of SUVs with soft tops, thus contributing perhaps to figures about injury from roll-overs.

So there are some caveats about the available figures, but on pollution, safety and the allegation that 4x4s clog up urban roads, what is the evidence that they are uniquely bad?

Drug Research

Also, the dog that does not bark.

How much evidence is suppressed that drug treatments do not work? And what about other research which finds nothing exciting or interesting? Not in aid of some commercial conspiracy, but as a routine part of the way we assess what is worthy of publication.

We talk to those who think we may be missing something and ask what are the consequences of neglecting the dull results.

Choice

And there is the cost of choice.

The cost?

Choice in the public sector, schools and hospitals, is supposed to improve efficiency and drive down costs.

But what if, in just one school, it had had the effect of doubling the cost per pupil?

Quiz answers

Plus, the results of last week's short quiz and listeners tackle some new questions.

Burglaries

First we asked a question about burglaries.

If, on average, terraced houses are more likely to be burgled than detached houses, how can it be true that a detached house on a street that is otherwise full of terraced houses can be more likely to be burgled than the terraced houses that surround it?

Answer: The probability of burglary is higher in areas with lower incomes.

There are more terraced houses than detached houses in areas with low incomes, so terraced houses are more likely to be burgled, on average, than detached houses.

But a detached house is easier to break into than a terraced house, and likely, on average, to have more valuable things to steal. So if a detached house is in the middle of a street of terraced houses, it is the detached house that is most likely to be burgled.

Sierra Leone

Question: The average life expectancy at birth in Sierra Leone is 34.

So how can it be true that a 20 year old in Sierra Leone is likely to live much more than 14 more years?

Answer: The average life expectancy in Sierra Leone is low because infant mortality is high, with many babies dying very early in life.

So the average life expectancy is pulled down by many with very short lives. Once past early childhood, individuals in Sierra Leone can expect, on average, to live to well beyond the age of 34.

Pregnancy

Question: Why are most pregnancies longer than average?

Answer: The average is reduced by premature births, some of which may be ten weeks early or even more.

Pregnant women in the UK have labour induced two weeks after the due date, so late births do not offset premature births.

Insurance

Question: On average we would be better off if we did not take out insurance. So why do we?

Answer: The reason we insure is that while most of us will not suffer catastrophic loss, so average losses are small, the loss for the person who does suffer is enormous.

We insure against the risk that we will be the ones who suffer the loss that is well above the average.


More maths stories from Plus magazine of the Millennium Maths Project can be found at

The BBC is not responsible for the content of external internet sites.

And more puzzles and problems at

The BBC is not responsible for the content of external internet sites.

More or Less was broadcast on Thursday, 17 February, 2005 at 1500GMT on BBC Radio 4.


Producer: Michael Blastland
Editor: Nicola Meyrick

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