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    Re: Weighted least squares
    From: Peter Fogg
    Date: 2010 Dec 19, 09:46 +1100

     P H wrote:

    The attached spreadsheet provides one way for averaging of sights.  Observation times go into column A and are considered exact. 

    One of the ways apparent outliers are created is by the mis-recording of time.  Its easy enough to do and just as likely to occur as writing down the incorrect altitude.  I know this because I've done both, and have also been affected by this vice when using a scribe to record observation data.  Since one number looks so like another this error may not be picked up during an averaging or linear-fit exercise.  However, if you graph those sights and compare them with the calculated (= true) slope, then such outliers immediately jump out and loudly exclaim:  "Hey, look at me!  Why do I stand out?  Hey!  What's going on here?"
    Notwithstanding this, your spreadsheet solution appears ingenious.  Of course, it presupposes having a spreadsheet to hand.  Comparison of slope with sights is not dependent on any electronics, since the slope can be derived graphically.
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