A famous statistical scare for the left-handed
British researchers (long ago) decided to see if handedness (as in being left-handed or right-handed) correlated in any way with life expectancy.
It shouldn't matter, right? At least we'd hope so.
Their approach was to contact all the hospitals and morgues in the region to ask that the survivors of the recently deceased make contact with them for their study. They asked for two facts about the death:
What was the age of death ?
What handedness was the deceased ?
After collecting extensive data they found the average age of death of left-handed people was younger than right-handed people.
This difference was statistically significant. In fact, it was as large a deficit of life expectancy as is found among people born with several well-known serious congenital diseases.
How could this be ? How could being left-handed shorten lives ?
Let me reassure any worried southpaws out there: Your condition is not killing you !
Never-the-less, this is what that study found. The study was done in good faith and was conducted in a generally competent and sound manner. The conclusion, however, came to be seen as one of the more infamous incidents in statistical analysis.
If you know this case, please refrain from any spoiler for now. For the rest of you I ask:
What went wrong here ?