Calculating the difference between two rasters as a percentage (not a raster) value

[ChristophersonPooter]

I am studying sand dune movements and have two sets of rasters for one area. After calculating the difference and multiplying by 100 to get a percent difference, I receive another raster set. Is there a way to present this data as a number value, so I can say for instance, the sand dunes changed XX% during this time period?

Is there another way I am not thinking of to present this data, any suggestions would be appreciated, this is for a final project in a college class I am taking. Thanks in advance!

[DanPatterson_Retired · Accepted solution]

As a single number? aren't you interested where the differences occurred? What is wrong with the absolute magnitude of volume change or showing areas of reduction and accumulation.  Percentages are often misused and I would avoid them unless they are accompanied by some tabular association with absolute values/magnitudes.

[DarrenWiens2]

I think you're probably looking for Zonal Statistics as Table, using a new raster covering the whole area as a single zone.

However, as Dan says, a single number might not describe your situation very well. For example, suppose you have a situation where you have a single dune covering the left 50% of your raster, and it moves to cover the right 50% of your raster. The left will all be -100% and the right will be all +100%, so the mean from Zonal Statistics as Table will be 0%, although there has been quite a bit of change.