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    Re: How good is St. Hilaire?
    From: Frank Reed
    Date: 2010 Mar 3, 11:54 -0800

    Andres, you quoted me as follows:
    "With a two-body fix, we can draw a confidence ellipse again based on the standard deviation of observations as an input. It's an ellipse about the same size as the "overlap box" for the error bands around each LOP. And with a three-body fix, this answers your concern about a confidence ellipse being drawn too small when the LOPs just happen by chance to coincide in a small triangle. That small triangle should not imply a small confidence ellipse, and it doesn't if the s.d. is an input rather than calculated from the observations themselves."

    And you replied:
    "An ellipse has 3 dof, degrees of freedom, thus without any assumption is not possible to plot it."

    Yes, right. So the s.d. has to be an input unlike the quoted solution that George and Herbert have been discussing. As I say, the quoted solution is just ONE way of looking at the problem. It's not scripture.

    -FER
    PS: By the way, in your post, you quoted me (the part above) by changing the color of the text. This is probably not a good idea. If you're going to quote someone, say "X said," or "Y wrote:" or use a block quoting function in your email software. You shouldn't use color because color is not respected as a syntactical property by web browsers and more especially by HMTL-capable email readers. Some will keep the colors. Some will ignore them or change them based on user preferences. In those that ignore or change them, there's no way to distinguish your comments from the original poster's words. It's not a big deal. Just wanted to let you know that the colors MAY get lost in translation.


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