Re:Former top executives of France Télécom on trial for hara...
by liberte82 on Wednesday July 10, 2019 @11:34AM
(#20402945)
> natural variance alone will push about 14% of random 22k samples into "more than double the base rate" area.
Is this true? Can you show the math on this? I'm not seeing it.
Re:Former top executives of France Télécom on trial for hara...
by praptak on Wednesday July 10, 2019 @01:48PM
(#20404423)
Nevermind, I made a mistake in my original calculations - used variance instead of standard deviation.
Actually (from approximating the binomial distribution with n=22k and p=17/22000 with normal one) getting the rate over 30 per 22k has p<0.001.
If the suicide rate is 17 per 22000, then natural variance alone will push about 14% of random 22k samples into "more than double the base rate" area.
In other words, if you take this indicator alone, then you'll have a false positive about 14% of the time. Obviously, the key word is "alone". With more data about bullying as the cause of suicide you might get better estimations.