Do percentages make sense?

[Coldicote]

From time to time I read news items such as: Falls in property prices slowed to 6.2% - 6.2% of what? Use of sunbeds raises the cancer risk by 75% - 75% of what? To me 75% means 'something' divided by a hundred and multiplied by 75. Without knowing what the 'something' figure is to start with it's meaningless to report in terms of percentages. How do other Abers interpret this kind of information?

[Sqad]

Coldicote....same as you mate.

e.g Gordon Brown has increased the helicopters in Afghanistan by 60%...........meaniningless.

What is 50% of nothing?............LOL

Negative growth........LOL

Don't worry.

[rov1200]

Squad are you aware that LOL usually means 'Laughing out Loud' unless there is some other meaning I'm unaware of?

[R1Geezer]

They also don't always mean percent they mean percentage points. Eg they often say things like "inflation has dropped 1 percent" what they mean is that it has dropped 1 percentage point.

In the cases you specify the property prices one means that based on last years prices today's are 93.8% of that.

In the sunbed case it is more of a probability figure than a percentage, they are saying that a sunbed user is more likely to get skin cancer than a non sunbed user by 1.75 ie 100% would be twice as likely.

[jno]

percentages generally make more sense the more details you give. I think Geezer has read the property prices one correctly but who knows if it's yearly or monthly?

Sometimes if you read a news story to the end you will find more details further down.

[youngmafbog]

Stats and the results in this case percentages can be manipulated into how the presenter wants you to see them. Unless you do know the whole facts ignore them

[Coldicote]

Thanks everyone. I'm beginning to see the light a bit better now - but never was brilliant at maths anyway. I just hope some of the people who churn out these percentage figures, or points, might read these comments and be a bit more specific in saying what they mean.

[scotman]

This is one of the techniques used by politicians and civil servants who are trying to obscure rather than illuminate.
There is a very good book called "The Tiger That Isn't" which has a section on this type of usage. It is good reading.

[Sqad]

rov....yes....LOL

[New Judge]

Let�s have a look at one of the examples you quote and see if I can help.

�Falls in property prices slowed to 6.2% - 6.2% of what?�

Property price changes are measured monthly and the annual change is the one usually quoted. So if average house prices were, say �100,000 last year (a bit low, I know, but it makes the numbers easy) and they are now �95,000, then they fell by �5,000 on a base of �100,000 which equals 5%. So the average price this year is 5% lower than the average last year. If they fall by another �5,000 in the following year, this time the base figure is �95,000, so the fall is 5,000 divided by 95,000 which is 5.26%. So the statement you mentioned explains that property prices have fallen by 6.2% in the last year and that this fall is less than had been measured previously.

�Percent� is simply a way of reducing the base to 100. In the example above It is easier to say five percent than five thousand one hundred thousandths, or five thousand ninety-five thousandths. Percentages are not designed to obscure as scotman suggests. On the contrary, they are used to make understanding simpler.

With any sort of statistical quote you have to understand a bit of the background to the issue under discussion so that you can interpret the figures sensibly.

[TCL-MUMPING]

If it is said inflation has fallen 1% and it had been 10%, does that mean it is now 9% or 9.9%? Reporters often say it has fallen by A% from B to C%, why can they not just say it has fallen from B to C%?

What winds me up is when folk say four times less (for example) when what they mean it is 1/4 of what it was.