On Sun, 1 Aug 2010, ted.hard...@manchester.ac.uk wrote:
On 01-Aug-10 10:59:03, Tims Corbett wrote:
Hi, What does it mean to say Lognormal distribution with a mean of
1.03E-6 with a range factor of 100 ? How can I find the lognormal
distribution paramters from this information?
Thanks, Tims
If you can, please say what is meant by "range factor". I have seen
it used to denote the ratio maximum/minimum for a sample, but it
might be intended to mean something else in the context of your
question.
Tim, you should learn to use Google to answer this question instead of
sending postings like this to lots of differnt mailing lists.
Googling
lognormal "range factor"
easily turns up the definition of range factor as a function of the
quantiles of the distribution.
FWIW, "Range factor" looks like a term of art used in certain circles.
RSiteSearch'ing (or just "??lognormal", for crying out loud!) turns up
everything else needed to answer this, viz the R functions to find the
quantiles, and even the relation between the mean of the lognormal and its
parameters.
I think a little bit of algebra makes it possible to solve this directly
from tables of the normal (or lognormal) even without having to resort to
uniroot().
Is this homework?
HTH,
Chuck
p.s. can the posting guide advise that OT questions like this be preceeded
by a suitable amount of Googling before coming here??
If it does mean that, then the context is a sample of values, deemed
to be log-normally distributed, with (presumably) the sample mean
equal to 1.03E-6 (0.00000103) and max/min=100. However this would
be really inadequate information to determine what the parameters
of the log-normal distribution might be. At the very least one needs
also the sample size, and even then the determination would not be
reliable.
Ted.
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E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk>
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Date: 01-Aug-10 Time: 12:33:45
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