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    Linear Regression In Reverse
    From: Peter Fogg
    Date: 2005 Jun 5, 08:08 +1000

    George has written, on the process of LINEAR REGRESSION IN REVERSE:
    
    > I just don't understand what Peter is proposing here. My fault, rather
    > than
    > his, no doubt.
    >
    > Could he provide a bit more detail, please, perhaps with an example?
    > Couldn't the moment, at which the Sun was theoretically on the East-West
    > line, be precalculated ...
    
    Yes, precalculation is what I am proposing, to give the moment of east or
    west azimuth (prime vertical).
    
    Then a series of observations of the body (it can be any celestial object
    for which almanac data is available, just as observation of meridian passage
    can, in theory, be made with any body).
    
    From then on it is the application of what seems a favourite hobby-horse of
    mine, comparing the slope with the sights. Its something I have written
    about here time and again; once with the title 'Good Data from Bad'. Now
    there's an approach you can appreciate.
    
    The practical advantage here is that it is not necessary to manage to make a
    timed observation at exactly the precalculated moment. So long as a series
    of sights encompasses that moment the time can be selected later from the
    graphed time axis and related, via the slope, to its accompanying altitude
    on the other axis.
    
    Rather than churn out more words I would encourage you to provide your own
    example, just as I have with Fred. Give it a whirl. I hesitate to say much
    more; for fear of becoming a bore just banging on about his id?e fixe, but I
    will say that the moment I understood this slope method was an Eureka moment
    for me and it has become part of the process of timed sights, just like
    recording the compass bearing of the body at the time of observation. Good
    or bad, the only reason I do these things is because they work a treat.
    
    How do you like the new name: LINEAR REGRESSION IN REVERSE. Nifty, huh?
    
    
    

       
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