What can we say about QQPlot of this data ?

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SUMMARY

The discussion focuses on the analysis of QQPlots for two datasets tested against a normal distribution. QQPlot 1 indicates non-normality due to excess data in the tails, while QQPlot 2 appears approximately normal but is discrete rather than continuous. The Jarque-Bera (JB) test results show that only a few datasets similar to the second QQPlot pass the normality test, with p-values ranging from 0 to 0.782. This highlights the subtle differences in data distribution despite similar QQPlots.

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  • Explore the implementation of QQPlots in R using the 'qqnorm' function
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Statisticians, data analysts, and researchers interested in data distribution analysis and normality testing will benefit from this discussion.

paawansharmas
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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
 

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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.
 
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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