Results 1 to 2 of 2
Like Tree1Thanks
  • 1 Post By Debsta

Thread: Correlation coefficient

  1. #1
    Newbie
    Joined
    Mar 2019
    From
    You can find me in Tussent
    Posts
    6

    Question Correlation coefficient

    I don't understand correlation coefficient well and I have few questions related to it.

    1)Can I say that correlation is based on slope concept?
    2)Does the correlation coefficient show how much are data points scattered on the plane?
    3)Correlation varies between -1 and 1. Does this mean that the line with a slope larger than 1 or smaller than -1 (e.g. 1000, -320) will have correlation of 1 or -1?
    4)What if I have a line y=5 (slope of which is zero) or x=5 (with undefined slope)?
    5)If I have data points very near to each other but they don't form any specific line, does this mean that the scatter plot will have correlation coefficient of zero?
    Last edited by Jotaro; Apr 27th 2019 at 02:13 AM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2009
    From
    Brisbane
    Posts
    1,237
    Thanks
    456

    Re: Correlation coefficient

    1. No, correlation is not based on slope. The correlation coefficient r lies between -1 and 1. If r=1 then the points on the scatterplot lie in a perfect upward sloping straight line. If r is say 0.9 the points would lie roughly in an upward sloping straight line, but not perfectly. The closer r gets to 0 the more "scattered" the points are ie they'll be a bit all over the place.
    If r=-1 the points will lie in a perfect downward sloping straight line
    2. Yes, see comment for 1
    3. No, the slope of the regression line has nothing to do with r. r is a measure of how well the regression line fits the points.
    4. Won't happen with useful data.
    5. No if you increase the scale on your axes ie zoom in you may or may not see the points lying along or close to a straight line.

    Best thing for you to do is to google Pearson's correlation coefficient - there are some excellent explanations out there. eg https://www.spss-tutorials.com/pears...n-coefficient/
    Thanks from Jotaro
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Correlation coefficient
    Posted in the Statistics Forum
    Replies: 2
    Last Post: Jun 22nd 2017, 08:05 AM
  2. Replies: 0
    Last Post: Feb 25th 2011, 12:15 AM
  3. Replies: 1
    Last Post: Dec 11th 2010, 10:16 PM
  4. Correlation coefficient.
    Posted in the Statistics Forum
    Replies: 3
    Last Post: Jun 1st 2010, 04:02 PM
  5. Correlation Coefficient - Have I done this right?
    Posted in the Statistics Forum
    Replies: 4
    Last Post: Jan 13th 2008, 07:38 AM

Search Tags


/mathhelpforum @mathhelpforum