# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Cocked hats, again.
From: Gary LaPook
Date: 2007 Mar 15, 14:24 -0700

```Gary LaPook wrote:

See my March 6th post.

You can draw circles around the fix plotted in the center of the
cocked hat of various radii to show the probabilities of your actual
position. When the triangle is small it may lie entirely inside a
particular probability circle, such as the CEP, so the portion inside
the circle but outside the triangle are possible positions. When the
triangle is very large all the probability circles will be contained
within the triangle so all positions must also be within the triangle.
This is an alternate way to describe the situations that I described
in my post of today, March 15th and illustrated in the diagrams.

On Mar 15, 2:05 pm, "P F"  wrote:
>  George Huxtable advocates this "simple message":
>
> >  "Plot a point, at the centre
> > of the triangle, but be aware that the true position could lie well
> > outside that triangle."
>
> Since this is a somewhat "tendentious" (lovely word, that) argument
> about statistics, isn't the chance of the "true position" lying within
> one standard deviation of a position line about 70% ? (Whilst
> retaining the assumption of a standard distribution of error.)
>
> And within two standard deviations about 90% ?
>
> What evidence can you present, George, for the "true position" being
> at all likely to lie "well outside" the triangle - or other shape?
>
> Is it not correct that the most likely place to find this "true
> position" is close to the position line?

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