"Statistics are like bikinis. What they conceal is more important than what they reveal."
CALCULATOR : POPULATION SCREENINGS
Are you in favour of large-scale (health) screenings? Does preventive screening for breast and prostate cancer, cardiovascular disease, diabetes and kidney functioning seem like a good idea to you? Think again...
No test is 100 per cent accurate. You may end up with a lot of 'sick' people who are, in fact, healthy. Even an extremely accurate test will still perform badly in very large populations and in populations where only very few people are expected to be sick.
Not convinced? Well, find out for yourself. Fill in the numbers and do the math!
Number of people:
True positives are patients who have been accurately tested as being sick. False positives are healthy patients who have been inaccurately tested as being sick. They may be treated for a disease they do not have.
True negatives are patients who have been accurately tested as being healthy. False negatives are sick patients who have been inaccurately tested as being healthy. They may not get the treatment they need.