I am using ArcGIS 10.3 with spatial analyst. I have a series of several rasters that I am trying to combine into a single raster layer. The rasters are all different sizes (different extents) and were produced using different sample sizes. I need to combine all these rasters using a weighted average based on sample size. Some of the rasters overlap, and others don't. At least one of the rasters is large enough to encompass all of the others. All have the same cell size and floating point values. I have tried using the Raster Calculator (i.e. (([raster1]*weight1) + ([raster2]*weight2))/sum of weights) as well as Weighted Sum. In either case, the output is reduced to the extent of the smallest raster, even when setting the processing extent to the same as the largest layer.
Are these approaches (raster calculator, weighted sum) appropriate to do a weighted average and combine these rasters?
What do I need to do to get the output to encompass the entire study area, and not just the extent of the smallest layer?