At the beginning of the twentieth century, H. G. Wells predicted that statistical thinking would be as necessary for citizenship in a technological world as the ability to read and write.
"A device has been invented for screening a population for a disease known as psylicrapitis.
2) The device is a very good one, but not perfect.
3) If someone is a sufferer, there is a 90 percent chance that he will be recorded positively.
4) If he is not a sufferer, there is still a 1 percent chance that he will be recorded positively.
5) Roughly 1 percent of the population has the disease.
6) Mr. Smith has been tested, and the result is positive.
The chance that he is in fact a sufferer is ______. "