Results 1 to 2 of 2

Math Help - rank correlation

  1. #1
    Newbie
    Joined
    Dec 2008
    Posts
    12

    rank correlation

    why while calculating rank correlation coefficient for tied ranks we take the average of the tied ranks to rank the same observations

    for eg.
    X : 29 30 25 30 30 45
    rank : 5 3 6 3 3 1

    why should we give the rank 3 (2+3+4)/3 for all the three 30's instead of

    2, 3 & 4. Can any one explain me the logic
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,807
    Thanks
    116
    Quote Originally Posted by Zandra View Post
    why while calculating rank correlation coefficient for tied ranks we take the average of the tied ranks to rank the same observations

    for eg.
    X : 29 30 25 30 30 45
    rank : 5 3 6 3 3 1

    why should we give the rank 3 (2+3+4)/3 for all the three 30's instead of

    2, 3 & 4. Can any one explain me the logic
    If you have a sorted list you can connect each value with an index. If there are equal values they should have equal indices (=ranks) too. Therefore you take the average of those ranks which belong to equal values. Thus it could happen that you have a rational number as rank (which is, at first sight, not very plausible)

    Btw there is a slight mistake in your calculation. (see attachment)
    Attached Thumbnails Attached Thumbnails rank correlation-list_ranks.png  
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. rank correlation
    Posted in the Statistics Forum
    Replies: 0
    Last Post: June 23rd 2011, 07:44 AM
  2. Calculating the Rank Correlation Coefficient
    Posted in the Statistics Forum
    Replies: 0
    Last Post: March 9th 2011, 06:54 AM
  3. Average rank correlation coefficients
    Posted in the Advanced Statistics Forum
    Replies: 0
    Last Post: April 12th 2010, 02:41 AM
  4. Replies: 1
    Last Post: August 6th 2007, 09:20 PM
  5. correlation and rank
    Posted in the Statistics Forum
    Replies: 2
    Last Post: July 30th 2007, 12:34 PM

Search Tags


/mathhelpforum @mathhelpforum