Ln mean

Ln mean is the mean of the natural logs of the values in the graph. Geological data is often distributed log-normally. The log-normal distribution is defined as follows

If the natural logarithm of a variable has a normal distribution then that variable is said to have a log-normal distribution.

The mean () of a lognormal distribution is defined as:

where is the mean of the data in the graph and is the variance of the data.

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The mean of a log-normal distribution is based on theory and it is generally accepted that the sample must contain at least 100 values and preferably more than 1000 values if this theoretical value of the mean is to have any meaning.