The ozone data is unimodal but is not very close to a normal distribution as seen in the histogram.• The normal QQ plot also shows that the data is not normally distributed, since the points in the plot donot form a straight line. A data transformation may be necessary.• Using the Trend Analysis tool, you saw that the data exhibited a trend and, once refined, identified thatthe trend would be best fit by a second-order polynomial.• The semivariogram/covariance cloud illustrated that the unusually high semivariogram values arelargely represented by the lines perpendicular to the coast. The analysis using this tool indicates thatthe interpolation model should account for anisotropy.• The semivariogram surface indicates there is spatial autocorrelation in the data. Knowing that thereare no outlier (or erroneous) sample points in the dataset, you can proceed with confidence to thesurface interpolation. You will be able to create a more accurate surface than the one you created inexercise 1 using default options and parameter values because you now know that there is trend andGeostatistical Analyst TutorialCopyright © 1995-2010 ESRI, Inc. All rights reserved. 30anisotropy in the data and you can adjust for it in the interpolation. Also, a data transformation mayimprove the prediction model.