What is the equation for the curve fit applied to the Probability plot?
For the curve fit applied to the Probability plot, you will get an equation of the form:
where a = median and b = standard deviation (if the data is normally distributed).
If the data is normally distributed, the median value reported by the curve fit should be the same as the median value of the raw data. If they differ, either the data is not normally distributed or does not follow this type of distribution.