Spatial Join Returns Nothing and the Map Is Empty
An analyst has a point file of 12,000 store locations with latitude and longitude stored as strings in Lat and Lon columns (e.g., "40.7128", "-74.0060"). They also have a polygon file of sales territories in a .shp. The analyst uses Create Points with Lat and Lon, then a Spatial Join to assign each store to a territory. The Spatial Join returns zero matches, and the Map tool shows points clustered in the ocean off West Africa. The analyst is certain the coordinates are correct because they match a spreadsheet. The workflow needs to produce a store-to-territory mapping.
1. What is the most likely cause of points appearing off West Africa, and how do you correct it before re-running the spatial join?
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Points clustered near (0,0) off West Africa almost always means the latitude and longitude were swapped, or one or both coordinates were read as zero/null. In Create Points, the X field is longitude and the Y field is latitude. If the analyst put Lat in X and Lon in Y, New York (40.7128, -74.0060) becomes X=40.7128, Y=-74.0060-a point off the coast of Africa. Also confirm the fields are numeric: if Lat/Lon were read as strings, Create Points may coerce them to 0, placing points at (0,0). Fix: use a Select or Formula to cast Lat and Lon to Double, then in Create Points set X = Lon and Y = Lat. Verify by checking a known point (e.g., a New York store should land near 40.7, -74.0) in a Browse or Map before the join. Only after the points are in the correct hemisphere should the Spatial Join be re-run.
2. After fixing the coordinates, the Spatial Join still returns fewer matches than expected-some stores near territory borders are unmatched. What explains this and how do you handle it?
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Spatial Join matches on spatial relationship (e.g., point within polygon). Stores that fall exactly on a border, in a gap between territories, or slightly outside a polygon due to coordinate precision will not match an 'within' predicate. Options: (1) Use a 'nearest' or 'distance within' spatial match with a small tolerance (e.g., within 100 meters) as a fallback for unmatched points. (2) Check the polygon file's spatial reference and ensure it matches the points' spatial reference; a mismatch in projection can shift points relative to polygons. (3) Inspect the unmatched points on a map against the polygons to confirm they are genuinely outside territory boundaries (e.g., coastal stores, PO boxes). (4) Decide business rules for border cases: assign to the nearest territory centroid or flag for manual review. The output should include a match-status field so unmatched stores are visible rather than silently dropped, and the count of unmatched should be reconciled against the expected total.