Loading ...
Sorry, an error occurred while loading the content.

1791Re: [ai-geostats] Re: F and T-test for samples drawn from the same p

Expand Messages
  • Chaosheng Zhang
    Dec 7, 2004
    • 0 Attachment
      Dear Isobel,

      Thanks for the information. Perhaps I didn't explain my request clearly.
      What I need is to verify the ideas you suggested in the previous message.
      Specifically, (1) Has anybody used the sill values (in geostatistics) to
      replace the variances (in classical statistics) in F test? (2) Has anybody
      used the global standard errors (in geostatistics) to replace the mean
      standard errors (in classical statistics) in t-test?

      Cheers,

      Chaosheng


      ----- Original Message -----
      From: "Isobel Clark" <drisobelclark@...>
      To: "Chaosheng Zhang" <Chaosheng.Zhang@...>
      Cc: <ai-geostats@...>
      Sent: Monday, December 06, 2004 6:03 PM
      Subject: [ai-geostats] Re: F and T-test for samples drawn from the same p


      > There ws a pretty good paper on global standard errors
      > in the 1984 APCOM proceedings, so I am sure it should
      > be in the major textbooks by now.
      >
      > Commparing the sills is very straightforward, I think.
      >
      > Isobel
      > http://geecosse.bizland.com/books.htm
      >
      > --- Chaosheng Zhang <Chaosheng.Zhang@...>
      > wrote:
      > > Isobel,
      > >
      > > Good idea, and that's a step forward. Any references
      > > or is it still an idea?
      > >
      > > Cheers,
      > >
      > > Chaosheng
      > >
      > > ----- Original Message -----
      > > From: "Isobel Clark" <drisobelclark@...>
      > > To: "AI Geostats mailing list" <ai-geostats@...>
      > > Sent: Monday, December 06, 2004 1:07 PM
      > > Subject: Re: [ai-geostats] F and T-test for samples
      > > drawn from the same p
      > >
      > >
      > > > Dear all
      > > >
      > > > I am having difficulty understanding why none of
      > > you
      > > > want to try a spatial approach to statistics.
      > > Everyone
      > > > is trying to make the 'independent' statistical
      > > tests
      > > > work on spatial data. Try turning this around and
      > > look
      > > > at the spatial aspect first.
      > > >
      > > > (1) Testing variances: the sill on the
      > > semi-variogram
      > > > (total height of model) is theoretically a good
      > > > estimate for the sample variance when
      > > auto-correlation
      > > > or spatial dependence is present. Do your F test
      > > on
      > > > that. Yes, you still have degrees of freedom
      > > problems,
      > > > but with thousands of samples the 'infinity
      > > column'
      > > > should be sufficient.
      > > >
      > > > (2) Testing means: the classic t-test in the
      > > presence
      > > > of 'equal variances' requires the 'standard error'
      > > of
      > > > each mean. For independent samples, this is
      > > s/sqrt(n).
      > > > For spatially dependent samples, this is the
      > > kriging
      > > > standard error for the global mean. Your only
      > > problem
      > > > then is getting a global standard error.
      > > >
      > > > Isobel
      > > > http://geoecosse.bizland.com/whatsnew.htm
      > > >
      > > >
      > >
      > >
      > >
      > --------------------------------------------------------------------------
      --
      > > ----
      > >
      > >
      > > > * By using the ai-geostats mailing list you agree
      > > to follow its rules
      > > > ( see
      > > http://www.ai-geostats.org/help_ai-geostats.htm )
      > > >
      > > > * To unsubscribe to ai-geostats, send the
      > > following in the subject or in
      > > the body (plain text format) of an email message to
      > > sympa@...
      > > >
      > > > Signoff ai-geostats
      > > >
      > >
      > >
      > > > * By using the ai-geostats mailing list you agree
      > to
      > > follow its rules
      > > ( see
      > > http://www.ai-geostats.org/help_ai-geostats.htm )
      > >
      > > * To unsubscribe to ai-geostats, send the following
      > > in the subject or in the body (plain text format) of
      > > an email message to sympa@...
      > >
      > > Signoff ai-geostats
      >
      >


      ----------------------------------------------------------------------------
      ----


      > * By using the ai-geostats mailing list you agree to follow its rules
      > ( see http://www.ai-geostats.org/help_ai-geostats.htm )
      >
      > * To unsubscribe to ai-geostats, send the following in the subject or in
      the body (plain text format) of an email message to sympa@...
      >
      > Signoff ai-geostats
      >
    • Show all 6 messages in this topic