Letter: At risk of baffling everyone
Sunday 13 April 1997
Wolpert argues that even experts can be irrational and uses a brain teaser about probability to illustrate this: a disease affects 1 per cent of people. The probability that a test will detect it is 80 per cent but has a 10 per cent false alarm rate. Given a positive test result, what is the probability that a patient has the disease?
Although even Harvard medical school staff have difficulties with this, most undergraduates readily provide the correct answer to the same problem described with frequencies because then it is easy to "see" the answer. Imagine 1,000 people (think of a 100 x 10 grid). Only 10 people will have the disease and eight of these a positive test. Tests on the other 990 will give 99 false positives. The answer is clear: eight of the 107 with a positive test have the disease.
There are reports of surgeons in the US performing "preventative mastectomies" on the basis of faulty reasoning with probability of cancer. There are easier ways of talking about risks than by using baffling mathematical nomenclature.
Life & Style blogs
Men in tights: getting to the bottom of the latest trend
Night Nurse could put drivers over new drug limit
Snapchat removed the Best Friends list feature and 'stalkers' are upset
Baldness could soon be treated using stem cells, scientists hope
Xbox Live down: gaming service breaks itself, but hackers claim credit
9 reasons Greece's experiment with the radical left is doomed to failure
Have we reached 'peak food'? Shortages loom as global production rates slow
Greece elections: Syriza and EU on collision course after election win for left-wing party
British grandmother Lindsay Sandiford faces execution by firing squad in Indonesia
Liberal Democrat minister defends comments suggesting immigration causes pub closures
King Abdullah dead: We can't afford not to hold Saudi Arabia's royals to account
- 1 Venezuela Expo Tattoo 2015: Extreme body art from 'Vampire Woman' to 109mm earlobes
- 2 Saudi preacher who 'raped and tortured' his five -year-old daughter to death is released after paying 'blood money'
- 3 Ball pool for adults opens in London
- 4 Game of Thrones season 5 trailer: The first full-length look is here
- 5 Rashida Jones speaks out against male-centric porn saying 'women should have sex and feel good about it'
£20000 - £35000 per annum: Recruitment Genius: This fast growing reinforcing s...
Excellent Package: Austen Lloyd: CITY - HIGHEST QUALITY INTERNATIONAL FIRM - A...
Excellent Package: Austen Lloyd: CITY - EXCELLENT FIRM - We have an outstandin...
Excellent Package: Austen Lloyd: IN-HOUSE - NATIONAL CHARITY - An exciting and...