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

1792[ai-geostats] Re: F and T-test for samples drawn from the same p

Expand Messages
  • Isobel Clark
    Dec 6, 2004
    • 0 Attachment
      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
    • Show all 16 messages in this topic