About the Standard Deviation Value

Standard deviation is a measure of variance or dispersion of values from a mean or average. It describes how a set of values such as elevations are distributed from a central value commonly called the average or mean. If outliers (values either much higher or lower than the other values) are present in the distribution of elevations, then the standard deviation of the values is higher than if the outliers were not present. Using the standard deviation method of calculating the minimum and maximum values reduces the effect of skew in the distribution of colors. If the distribution of elevation values has outliers that visually affect the color distribution, a low standard deviation value such as 2 will produce better results. If the visual effect of the outliers is not as significant, then a higher standard deviation value such as 3 or 4 are likely applicable values. Using low standard deviation values when outliers are not as prominent in the elevation values, will result in using too much color on either end of the spectrum. In contrast using high standard deviation values when outliers do have a significant impact on the distribution of colors will result in not enough colors on the ends of the spectrum.

How to Modifying the Standard Deviation Value

Standard Deviation Text Box

1. Open the Properties dialog.

2. Select the 'Symbology' tab and the 'Elevation' tab within it.

3. With the "Standard Deviation" type method selected, input a value greater than zero.

Selecting the Standard Deviation type method