## Multiple Grid Statistics

Option on Raster GIS,
Multiple grid arithmetic,
submenu.

Takes you to Grid tab of Options
form which lets you pick the grids to create and how to handle missing data.

Grids you can create, using all the open grids

- Ceiling: the highest point among the grids
- Mean: the average point among the grids
- Median: the point with half the grid values above, and half
below. For an odd number of grids, it will be the value in
one grid; for an even number of grids, the average between the
two middle grids.
- Floor: the lowest point among the grids
- Num Pts: the number of grids with a valid value (not
missing) at the point
- Envelope thickness: the difference between the ceiling and
floor values. This will show either the change in the grids,
or error.
- Grid with min: the index of the grid that has the lowest value. It
must be lower than all other by the specified tolerance.
- Grid with max: the index of the grid that has the highest value. It
must exceed all other by the specified tolerance.

A missing point in one grid can invalidate the result at a pixel,
which will also be missing, or if the program can do statistics with those grids
which have a value.

The resulting files will have the extent of the active map when you select
the option, and will have the same resolution.

*Last revised 1/8/2019*