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What can we say about QQPlot of this data ?

  1. Sep 26, 2012 #1
    This is the QQPlot of a data. What can be inferred from this plot ?
    (Tested against Normal Distribution)
    QQPLOT 1 :
    attachment.php?attachmentid=51211&stc=1&d=1348650222.png

    QQPLOT 2:
    attachment.php?attachmentid=51212&stc=1&d=1348650379.png
     

    Attached Files:

    • qq1.png
      qq1.png
      File size:
      4.7 KB
      Views:
      100
    • qq2.png
      qq2.png
      File size:
      4 KB
      Views:
      104
  2. jcsd
  3. Sep 26, 2012 #2
    The first one is not normal - there is more data on the tails than there would be in a normal distribution.

    The second one looks approximately normal, except for the fact that it is discrete instead of continuous.
     
  4. Sep 27, 2012 #3
    thnks mxscnt

    Jaque-Bera tests failed for first dataset.
    while for data sets similar to second one, few were passing JB test for normality.

    these are the p-values for JB test for 14 data sets similar to second graph.

    P-VALUE
    0.005
    0.039
    0.003
    0
    0.00287214
    0.595792
    0.190489
    0.0947931
    0.782434
    0
    0.12
    0.257
    0.656
    0.246

    you can see almost 3 sets qualify for normality.

    Though there QQPlot are almost similar.

    What can be the reason for difference ???
     
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