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Re: AI-GEOSTATS: transformation of data

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  • Edzer J. Pebesma
    Dear Sibylle, I suspect your residuals will never become normal, because your data are counts. Luckily, normality is not a requirement for variogram
    Message 1 of 2 , Apr 9, 2002
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      Dear Sibylle,

      I suspect your residuals will never become normal, because your data
      are counts. Luckily, normality is not a requirement for variogram
      calculation nor for kriging interpolation.

      However, before calculating variograms it may be a good idea to
      correct for non-stationarity in the variances, and work with Pearson
      residuals.

      See:

      Gotway, C.A., Stroup, W.W. (1997) A Generalized Linear Model Approach
      to Spatial Data Analysis and Prediction. Journal of Agricultural, Biological
      and Environmental Statistics 2(2), pp. 157--178.

      Diggle, P.J., Liang, K-Y., Zeger, S.L. (1994) Analysis of Longitudinal
      Data. Oxford University Press, Oxford.

      or the more advanced approach of:

      Diggle, P.J., J.A. Tawn, R.A. Moyeed (1998), Model-based
      geostatistics. Applied Statistics 47(3), pp 299-350.
      --
      Edzer

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