NavList:

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Hello Greg,

Please take a look at these links:

http://www.navigation-spreadsheets.com/alt_corr.html#average1
http://www.navigation-spreadsheets.com/alt_corr.html#average2

What I describe there is different, because in my spreadsheets the fits are computed rather than guided by eye looking at a plot.  Nevertheless, it is related to what you are trying to do, so you may find it useful.

A few years ago we had extensive discussions on NavList about precisely this topic.  You may use NavList's search engine (thanks, Frank!) to look for threads named "Kurtosis", "Weighted least squares", and "Rejecting outliers" which started around December 2010.


Peter Hakel

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From: Greg Licfi <cfi{at}licfi.com>
To: pmh099---.com
Sent: Friday, January 24, 2014 6:03 PM
Subject: [NavList] Need help writing a slope-fit excel sheet

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Hi all,
      I read a article by David Burch concerning sight averaging with (I
believe) the intent on improving
the sights taken with plastic sextants. Mr. Burch believes that this
technique should be applied to metal
sextants to improve overall accuracy. One of the things he suggested is
doing a slope-fit of the multiple
sight data to kick out not-so-obviously-bad data points. It all makes
sense to me. I started to write a slope-fit
excel sheet (which eventually I can use on my smart phone) There are two
plots: one is the sight data
in BLUE, the second is a Hc for the start & stop times of the sights it
is in RED. ultimately you will be able to
slide the RED Hc plot up or down to see if the sight data points fit the
slope. I'm stuck getting the buttons
to work. I would ask if there are any excel mavens on the list if they
could look at my attached sheet and
help me activate the cursor up/down buttons; I'm not super knowledgeable
on macros. Once that is figured
out it should be quite handy for isolating bad sights.
Many Thanks In Advance!
~Greg

P.S.
Typically how many sights on average should one take, and over what time
span?

Attached File:

(img/126689.slope fit.xls: Open and save or View online)

: http://fer3.com/arc/m2.aspx?i=126689

: http://fer3.com/arc/m2.aspx?i=126691