ArcGIS v.10.3.1 for Desktop.
I'm using the IDW (Spatial Analyst) tool to interpolate water quality data for the Island of Newfoundland. I wanted to impose a barrier to separate data collected on one side of a ocean bay from influencing results on the opposite side of the bay. The IDW tool output is wrong when imposing a barrier. For instance, the data range is incorrect (should be 0-63, not 0-13), and the input data does not correspond with the IDW output data classes. I've attached a PDF that shows the two IDW outputs: (1) no barrier imposed, and (2) barrier imposed.
Any idea what is happening when the barrier is imposed?