The trouble with confusing not observing with not existing

It seems like many have taken the reasonable statement

we identified the swine flu in Mexico last week, then we started looking else where and found it there too

and made the leap to

the swine flu first appeared in Mexico last week and since then has traveled to other countries.

The problem with the second statement is it makes it appear like the swine flu is traveling much faster than we actually have evidence to support. While me may have only been finding swine flu in those who have recently been to Mexico that may be because we have only looked at the people who have recently been to Mexico.

The same flaw in reasoning leads to people thinking that autism is on the rise. If you look for something somewhere you are far more likely to find it there.