https://community.esri.com/t5/spatial-statistics-questions/kriged-surface-showing-different-scale/m-p/1545570#M2678 <P>Hi&nbsp;<a href="https://community.esri.com/t5/user/viewprofilepage/user-id/324156">@MasoodShaikh</a>,</P> <P>Kriging is an "inexact" interpolation method, meaning that the prediction surface does not pass perfectly through the values of the input points and instead has a tendency to smooth predictions (meaning that the range of predictions is usually more narrow than the range of the original data values).&nbsp; The weaker the autocorrelation and the more noisy the data, the more it tends to smooth.&nbsp; For your data, it's likely that you have many locations where high values are very close to low values, and the kriging surface effectively smooths over the highs and lows.</P> <P>There are a couple things you can do.&nbsp; First, you can use an interpolation method like Radial Basis Functions (aka splines) or Inverse Distance Weighting that will always honor the range of the input data values.&nbsp;&nbsp;</P> <P>Second, you can disable the Nugget effect of kriging, which will force it to honor the input data range.&nbsp;&nbsp;You can do this on the semivariogram page of the Geostatistical Wizard by changing the “Model Nugget” option to “Disable”.&nbsp; However, not using a nugget effect can often create strange artifacts in the output, so it is generally not recommended.&nbsp; If you do this, pay close attention to strange behavior in the resulting surface.</P> <P>-Eric</P> Fri, 04 Oct 2024 13:39:15 GMT EricKrause 2024-10-04T13:39:15Z https://community.esri.com/t5/spatial-statistics-questions/kriged-surface-showing-different-scale/m-p/1545489#M2677 <P>I have data points (points shapefile) on the proportion of a certain disease, with values ranging from 0 to 1. After creating a kriged surface, the proportions ranged from 0.043 to 0.756. I need to understand why this discrepancy occurred.&nbsp;</P><P>For reporting these findings in a scientific journal, would it be appropriate to use a scale ranging from 0 to 1, with the lowest class being 0.00 to 0.10 and the highest class being 0.70 to 1.00? Additionally, are there any references that explain why a kriged surface can have a different scale and best practices for using them in the map legend?</P><P>Thank you!</P> Fri, 04 Oct 2024 08:21:24 GMT https://community.esri.com/t5/spatial-statistics-questions/kriged-surface-showing-different-scale/m-p/1545489#M2677 MasoodShaikh 2024-10-04T08:21:24Z https://community.esri.com/t5/spatial-statistics-questions/kriged-surface-showing-different-scale/m-p/1545570#M2678 <P>Hi&nbsp;<a href="https://community.esri.com/t5/user/viewprofilepage/user-id/324156">@MasoodShaikh</a>,</P> <P>Kriging is an "inexact" interpolation method, meaning that the prediction surface does not pass perfectly through the values of the input points and instead has a tendency to smooth predictions (meaning that the range of predictions is usually more narrow than the range of the original data values).&nbsp; The weaker the autocorrelation and the more noisy the data, the more it tends to smooth.&nbsp; For your data, it's likely that you have many locations where high values are very close to low values, and the kriging surface effectively smooths over the highs and lows.</P> <P>There are a couple things you can do.&nbsp; First, you can use an interpolation method like Radial Basis Functions (aka splines) or Inverse Distance Weighting that will always honor the range of the input data values.&nbsp;&nbsp;</P> <P>Second, you can disable the Nugget effect of kriging, which will force it to honor the input data range.&nbsp;&nbsp;You can do this on the semivariogram page of the Geostatistical Wizard by changing the “Model Nugget” option to “Disable”.&nbsp; However, not using a nugget effect can often create strange artifacts in the output, so it is generally not recommended.&nbsp; If you do this, pay close attention to strange behavior in the resulting surface.</P> <P>-Eric</P> Fri, 04 Oct 2024 13:39:15 GMT https://community.esri.com/t5/spatial-statistics-questions/kriged-surface-showing-different-scale/m-p/1545570#M2678 EricKrause 2024-10-04T13:39:15Z