Interpolating with multiple values for each x,y coordinate

[DebraParthree]

I am trying to interpolate water quality values for a volume of water where multiple measurements and varying depths (profile data) were taken at a single GPS coordinate.  So I have a table with repeating X/Y values where we measured dissolved oxygen values at different depths from surface to bottom at 80 locations.  I want to create a continuous raster from the point data that takes into account not just the surface or bottom but all measurements.  How do Spatial Analyst tools handle multiple values from the same X/Y coordinate?

[DarrenWiens2]

Off the top of my head, I'd combine your coincident points beforehand (ie. calculate the mean value, or whatever other statistic/weighting, with Summary Statistics, or Python, group by coordinates), then interpolate those values. Whether or not that has geostatistical implications, I don't know.

[SteveLynch]

Please check the help, below is a snippet from IDW's help.

Some input datasets may have several points with the same x,y coordinates. If the values of the points at the common location are the same, they are considered duplicates and have no affect on the output. If the values are different, they are considered coincident points.

The various interpolation tools may handle this data condition differently. For example, in some cases the first coincident point encountered is used for the calculation; in other cases the last point encountered is used. This may cause some locations in the output raster to have different values than what you might expect. The solution is to prepare your data by removing these coincident points. The Collect Events tool in the Spatial Statistics toolbox is useful for identifying any coincident points in your data.

Steve