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
    or...
       
    Reply
    Re: Golden Globe Race -- how would you detect cheating?
    From: Bill Lionheart
    Date: 2021 Apr 28, 09:05 0000

    Bob

    I think it might have been Bunsen who said "lack of mathematical education reveals itself nowhere better than in exaggerated arithmetic accuracy". However I am not sure if it is true as you claim that there is no point in reading measurements to a greater accuracy than the overall accuracy of a reading.

    Suppose you have a measurement process such as measuring an altitude by sextant and the random errors, due for example judging the sun touching the horizon and reading the time without delay etc are from some known distribution (for which Frank has an interesting suggestion). Suppose you then also truncate the digits of this measurement. This introduces roughly (again as Frank mentions some bias) uniformly distributed error. This changes the distribution of overall errors and I suspect will generally make the variance greater. By how much and is it enough to bother I am not sure in this case. But in some cases it matters.

    The (English) Wikipedia article on False Precision is interesting although far from comprehensive. It makes the point that you should round after you have done your calculations not during the measurement. In our case if you do a series of sights and want to use eg regression to improve the accuracy (this assumes the times were right but the altitudes have errors), then you would use all the digits you can read.

    Bill

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

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

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

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

    Email Settings

    Posting 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