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I am working in QGIS 2.18.14 to which i am fairly new. I am trying to perform a nearest neighbor analysis, however it returns 0 for the observed mean distance. the expected distance is also an absurdly small number:

Observed mean distance: 0.0 Expected mean distance: 8.02080627703e-05 Nearest neighbour index: 0.0 Number of points: 78 Z-Score: -16.8957775986

When I measure the distances between points using the Measure Line Tool i get normal values around 5-20 meters. My best guess is that since my points are in Lat-Long, it's performing calculations in lat-long instead of in meters, but i don't know why it would do that or how i could fix it. All layers are in the same CRS (WGS 84 EPSG:4326). with on-the-fly crs transformation off.

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First check the map units of the map document under View --> Data Frame Properties. Check that you're using units of meters under the General tab.

If that doesn't fix things try to project the raster into UTM and see if you get the same error.

  • So, I've switched my project into a UTM and am getting the same results but, my measured distances are now coming out much smaller. my 4.5km length island is now measuring at 4cm. – Dan.L Nov 27 '17 at 18:23
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    Dan.L, you have probably not transformed your data to UTM, just told QGIS (using "Set Layer CRS") that the data is in a UTM projection. QGIS will then assume that your coordinates are in meters instead of degrees. A distance of 1 degree in the north-south direction is about 111 km, but you have now told QGIS that it is 1 meter. – Håvard Tveite May 29 '18 at 23:47

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