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    Re: Rejecting outliers: was: Kurtosis.
    From: George Huxtable
    Date: 2011 Jan 2, 21:36 -0000

    I had written, earlier today, that-
    
    "That's by no means conclusive; no more than suggestive, that the
    calculated slope of 32 may be somewhat suspect. It would be worth checking
    it out once again, to be sure. The quoted latitude of 34� corresponds with
    the (South) lat. of his home port of Sydney, so is unlikely to be wrong,
    but what about the calculated azimuth of 149�? We haven't been given
    sufficient information to check that for ourselves; perhaps we can be
    provided with the missing details."
    
    But indeed, we were given the name of the body being sighted, as Canopus, 
    which does provide sufficient information to check out the azimuth and 
    therefore the calculated slope. And this really does turn out to be around 
    32' per 5-minute period, and not 24'. So imposing such a known rate-of 
    change, as in the second of the methods I listed, is a better way to go 
    than allowing the slope to be freely determined from the data, as in the 
    fourth method. However, neither will do any better than taking the simple 
    mean of amplitudes and times, as every such best-fit line, no matter what 
    its slope, must pass exactly through the mean point marked as P.
    
    George.
    
    contact George Huxtable, at george{at}hux.me.uk
    at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. 
    
    
    
    
    

       
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