Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Standard Deviation Question
    From: William Hawes
    Date: 2013 Jan 5, 12:53 -0800

    On 04 Jan 2013 at 21:00 Greg Rudzinski said:
    Here are 20 index error observations of Procyon using a Tamaya Jupiter with 7 x 35mm scope.
    0.2' 0.7'
    0.4' 0.7'
    0.4' 0.6'
    0.6' 0.4'
    0.8' 0.6'
    0.6' 0.7'
    0.7' 0.7'
    0.7' 0.4'
    0.7' 0.7'
    0.5' 0.4'
    x = 0.575'
    Sx = 0.1585'
    Greg, ran your data thru the TI-Nspire calculator. The results were

    stdDevSamp() > 0.1585 (agrees with your result)
    stdDevPop() > 0.1545

    Frank (in his 02 Jan 2013 at 16:33 posting re: "Lunars and accuracy generally") used a Population StdDev and you used (above) a Sample StdDev.

    I guess I still have the same question. When should we be using Pop and when should we be using Samp? I'm starting to believe, from what has been said in other replies, that since one is using "all" the observed data then the Pop Std Dev is the most appropriate. Also, as others have said, it may not make a lot of difference since the difference only shows up in the third decimal place of an accurate to one decimal place set of data.

    FYI, I've pulled out my old college statistics book and have started plowing thru it from the beginning - as virtually all of it has long been forgotton.

    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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