Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Linear regression and other tools
    From: Antoine Couëtte
    Date: 2018 Oct 11, 12:00 -0700

    Re : Linear-regression-other-tools-Morris-oct-2018-g43043 

    Dear Brad,

    The average value of a set - here observations times and heights - belongs to the linear regression of this set.

    For a given set of observations, if you are in a position to use only its average value, you are using the whole set to its best. In other words: you are using absolutely all information contained in this set, and you are not discarting any information contained in it.

    Hence - for CelNav at least - [absolutely] no need to "linear regress": simply "average".

    Whenever possible I personally recommend 5 observations for each and any celestial body over a maximum time span of 4 minutes of time, a duration during which second and higher order terms are always negligible - i.e. less than 0.1' - whatever the height observed. Essential reason for that ? 5 observations reduce random errors by a factor slighly above 2 (actually by the square root of 5). To reduce Random error by 3 would require 9 observations - by 4 would be 16 !!! - which is totally unrealistic as linear regression should then be replaced by at least 2nd Order Regression, which involves many more "guessing fitting" parameters.

    Also, up to 4 minutes devoted to one single Body, espacially at dawn or dusk remains acceptable. You should have plenty of time to "multi shoot" at least 2 extra bodies, or even 3 extra bodies.

    Observing and averaging 4 different bodies with 5 observations on each of them is an excellent practical trade-off between random error minimizing and the workload of 20 different observations.

    Antoine M. "Kermit" Couëtte

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site