Optional 95% confidence intervals for the bin counts are computed with the Clopper-Pearson method (see the Single proportion module for computational details).
The "Fit normal" option draws a graph with a fitted normal distribution (Parametric estimation, not Least Squares).
Kernel Density Estimation is a smooth estimator of the histogram. PAST uses a Gaussian kernel with range according to a rule given by Silverman (1986).
Missing values are deleted.