Posts Tagged ‘Damned Lies and Maths’

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2. My Mum Says Survey

October 12, 2010

Statistics

The SMALL SAMPLE error.

A survey is taken but the number of people surveyed is so small as to be irrelevant; not much better than simply asking your mum for her opinion and publishing the results.

Included here is a full-page Women’s Weekly (Oct 2010) ad for an Elizabeth Arden Anti-wrinkle Cream. Look at these wonderful statics. 92%… 85% …Wow! Look at the language. Gives eyes a ‘radiant and luminous look’ Sounds like the DEVIL!!!! Read the small print.

The survey was based on 30 participants and ‘results may vary’.

                            

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3. The Trouble with Double

October 12, 2010

Percentages

When the Numbers involved are so SMALL the % Stated is Meaningless.

Newspapers often state that a cancer rate has doubled or increased (See pic) by 28%. Those % changes can be meaningless. For instance, double nothing is still nothing. You need the actual numbers.

 

Here is a statistic taken from Men’s Health magazine (March 2010). According to the government funded Australian Institute of Health and Welfare the actual number of Australian males who presented with melanoma in 2005 was 6,044

or   0.549  in 1,000

or 1 in 2,000.

If these numbers increase by 28% the number of Australian men presenting with melanoma will be:

 

0.703 in 1,000

or  ~ 2 in 3,000.

These numbers are not so alarming. Then again would you take any notice of statistics of a magazine that suggests a ‘sonic boom’ from a golf club is causing deafness!!!!!