Imagine you are an insurer and advise free annual checkups. Some of your patients don't bother. Those patients have a higher mortality. You conclude the annual checkup is good.
But you might be deceiving yourself - the kind of people to ignore health advice about getting an annual checkup might also be the kind of people to ignore the health advice on the back of a cigarette packet...
Sure, they understand the problem... But is there anything they can do about it?
I'm not aware of insurance companies being too keen on getting into medical experiments like 'people with a birthday on a Thursday don't get the free annual checkup'.
Imagine you are an insurer and advise free annual checkups. Some of your patients don't bother. Those patients have a higher mortality. You conclude the annual checkup is good.
But you might be deceiving yourself - the kind of people to ignore health advice about getting an annual checkup might also be the kind of people to ignore the health advice on the back of a cigarette packet...