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    Re: Lat/Lon by "Noon Sun" & The Noon Fix PROVE IT
    From: James N Wilson
    Date: 2009 Apr 29, 08:56 -0700

    Brad:
    
    I'm sure that least squares is better, but I used regression analysis
    because that was what I had. I'm a complete novice at this mathematical
    curve fitting. I was grasping at straws to avoid asking for more data
    points. I've looked at a good many student sight plots, and they are
    almost uniformly on a straight line. But they are taken with a sharp
    horizon. I suspect that a hazy horizon would yield the kind of data that
    George generated.
    
    Being curious, I immediately tried this new toy on my ancient data
    example. It placed the ascending line in exactly the same place that I
    had eyeballed it, and had only a slight difference in the descending
    line. The net result was a slight improvement in accuracy. In eyeballing
    sights, I tend to throw out ones quite a ways from the trend, whereas any
    curve fitting algorithm will use them all.
    
    In looking at the final results, sights taken in runs centered around LAN
    would be more utile than ones taken around highest altitude. That would
    eliminate the extrapolation. But, as George points out, the observer
    doesn't know when LAN is yet. More sights could be taken, so that the
    latter ones would avoid extending the data lines outside of the range
    measured.
    
    I think that I still have a lot to learn.
    
    Jim Wilson
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