[Scipy-tickets] [SciPy] #1295: Confusing and/or inaccurate labels on probability plot ('stats.probplot') axes

SciPy Trac scipy-tickets@scipy....
Wed Oct 6 14:04:21 CDT 2010


#1295: Confusing and/or inaccurate labels on probability plot ('stats.probplot')
axes
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 Reporter:  jmpolom      |       Owner:  somebody
     Type:  defect       |      Status:  new     
 Priority:  normal       |   Milestone:  0.9.0   
Component:  scipy.stats  |     Version:  0.7.0   
 Keywords:  probplot     |  
-------------------------+--------------------------------------------------
 Problem: The SciPy probability plotting function (probplot) wrongly labels
 the resulting plot's x-axis as 'Order Statistic Medians'. The actual set
 of values plotted on the x-axis are ordered z-score transforms of each
 data point's median statistic, readily determined by examining the source
 in morestats.py. Likewise the y-axis label could be improved, since
 'Ordered Values' implies the data plotted is numeric. If the y-axis plots
 categorical or ordinal data, labeling it 'Ordered Values' is not exactly
 truthful.

 Context: A mislabeled x-axis prevents me from using SciPy's probability
 plotting features professionally without a little grief. Properly labeled
 axes are essential.

 Recommended Fixes: I recommend changing the label probplot assigns to the
 x-axis to simply 'Z-scores'. Updated documentation for probplot can
 explain what is plotted on which axis, and what statistic probplot
 computes. Finally, I recommend changing the default y-axis label to
 'Ordered Responses', which doesn't imply any specific type of data is
 plotted on the axis.

 I've attached sample probability plot output showing the mislabeled axes
 this ticket refers to. I've also attached an updated morestats.py file
 with the suggested fixes.

-- 
Ticket URL: <http://projects.scipy.org/scipy/ticket/1295>
SciPy <http://www.scipy.org>
SciPy is open-source software for mathematics, science, and engineering.


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