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# lognormal distribution watch

1. suppose I am given the median and the 95th percentile point of some data, which is lognormally distributed.

i have the inverse normal function to have, and nothing else special.

give an expression for 'sigma', where sigma is standard thing with a lognormal distrib, i.e. the s.d. of the log of our random variable (or, give the s.d. of the distribution itself, but i don't think this is easier..)

i get really confused with the lognormal distribution.
2. (Original post by Chewwy)
suppose I am given the mean and the 95th percentile point of some data, which is normally distributed.
.......or, give the s.d. of the distribution itself.....
I must be reading this wrong because it looks like a simple S1 problem.
3. (Original post by rnd)
I must be reading this wrong because it looks like a simple S1 problem.
sorry, i meant lognormally.. (and also median, not mean..)
4. (Original post by Chewwy)
suppose I am given the median and the 95th percentile point of some data, which is lognormally distributed.

Given median=A and 95th centile=B

and

???

Don't laugh..... I clearly don't have a clue what I'm doing

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