[docs] Make the documentation for statistics' data argument clearer. (issue 27825)

[mariatta.wijaya at gmail.com]

http://bugs.python.org/review/27825/diff/18782/Doc/library/statistics.rst
File Doc/library/statistics.rst (right):

http://bugs.python.org/review/27825/diff/18782/Doc/library/statistics.rst#newcode241
Doc/library/statistics.rst:241: >>> median_grouped([F(55, 7), F(52, 3),
F(53, 3), F(5, 3)])
On 2016/10/08 02:20:06, stevenjd wrote:
> I dislike this example as it is misleading.
> 
> median_grouped() will work with arbitrary numbers, as in this example,
but the
> intention is that the numbers are the mid-point of data classes, often
called
> "class marks". So you should expect that the data are equally-spaced
values
> (median_grouped assumes a class interval of 1 by default, but it can
be
> changed). Examples should be equally-spaced (possibly with gaps -- it
is okay if
> a class has no values).
> 
> Although median_grouped() will work with Fractions, I think it is
unlikely that
> anyone would give it actual data in Fractions. I'd prefer to see more
realistic
> examples: ints, floats or Decimals.
> 
> Perhaps the documentation needs to define the relevant statistics
terminology?
> "Class interval", "class mark", "class limits". See:
> 
> http://mathworld.wolfram.com/ClassMark.html
> 

Steven, thank you very much for the feedback.

I've been working on another patch that will address other comments
above. But since I'm not a statistician, I'm a bit stumped on how to
improve this particular example about median_grouped().

http://bugs.python.org/review/27825/