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Re: GEOSTATS: ASH - modeling technique

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  • J-F Lenain - L.A.S.E.H.
    ... ASH is special case of discretized kernel smoothing technique (WARPING): it use - discretized triangular kernel - same grid for both prebinning (data) and
    Message 1 of 3 , Oct 7, 1997
      >I have seen reference to a modeling method referred to casually as "ASH." I
      >know next to nothing and have only heard mention of this method as a faster
      >substitute to kriging with fewer distortions at the boarders. Could someone
      >point me to where to get information on this procedure.

      ASH is special case of discretized kernel smoothing technique (WARPING):
      it use
      - discretized triangular kernel
      - same grid for both prebinning (data) and postbinning (estimation
      and interpolation).

      estimating with linear interpolation in postbinning (plotting for ex.)
      is quite as accurate as usual kernel estimates: the ratio of bin width
      and kernel window must be <=1/5 in practice.
      HALL and WAND, 1996 : J. of Multivar. Anal., 56, 165-184 (prebinning)
      JONES, 1989 : J. Amer. Stat. Assoc., 84, 407, 733-741 (pre and postbinning)
      SCOTT, 1985 : Annals of Stat. , 13, 3, 1024-1040 (ASH, FP-ASH)

      using FFT for convolution is a very efficient way to compute ASH,
      and easy to program
      SILVERMAN, 1982 : Applied Stat., 31, 93-99
      JONES at al., 1984 : " " , 33, 120-122

      (rem: the above ref. are for density estimates)

      see also:
      HARDLE, 1991 : smoothing techniques - Springer
      for the warping approximation of Nadaraya estimate (p137..)
      (with code)
      SIMONOFF, 1996 : smoothing... - Springer
      for a wide bibliography
      HARDLE et al., 1995 : Xplore - Springer
      is the book of a program using ASH
      you can download Xplore from the web site
      http://www.xplore-stat.de/





      -----------------------------
      jean-francois LENAIN
      L.A.S.E.H.
      faculte des Sciences
      87060 Limoges CEDEX (France)
      e-mail: lenain@...
      -----------------------------

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