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How is this graph NEGATIVELY SKEWED

  1. Jan 4, 2012 #1
    1. The problem statement, all variables and given/known data
    http://www.thestudentroom.co.uk/attachment.php?attachmentid=103146&d=1306479703

    Look at question 3(d)
    and the graph for question 3
    how is this graph NEGATIVELY SKEWED


    2. Relevant equations



    3. The attempt at a solution
    I know that a -ve skew has a tail in the low x-values but I find it difficult to see that here :(

    (I am not sure what further attempt I can give, I have said everything I know about shapes of skewed curves I just cannot see why it is -ve. I was hoping someone could help me with this!)
     
  2. jcsd
  3. Jan 4, 2012 #2
    Re: Skewness

    Look at the answer to part c, a = 5.

    So the left tail is 3 units long and the right tail is 2 units long
     
  4. Jan 4, 2012 #3
    Re: Skewness

    I always though the tail was a flat bit? how does the tail relate to the median / mode
    is it as follows:
    the mode is assumed to be the middle of the graph
    if the a<x<mode is greater than mode<x<b for a graph a<x<b then it is negative skew
    if a<x<mode is less than mode<x<b then the graph for a<x<b is +ive skew?
     
  5. Jan 4, 2012 #4
    Re: Skewness

    Sorry I was in the wrong part of my book for the answer, ok not much help but my book says

    Negative skew = Mean < Median < Mode.

    Positive skew = Mean > Median > Mode.
     
  6. Jan 4, 2012 #5
    Re: Skewness

    Then you can deduce that because the area of both sides of the mode is the same, then the mean will lie on the longer side.
     
  7. Jan 4, 2012 #6
    Re: Skewness

    oh I see
    ok
    thanks
     
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