bpo-36018: Add documentation link to "random variable" (GH-12114)
https://bugs.python.org/issue36018
diff --git a/Doc/library/statistics.rst b/Doc/library/statistics.rst
index 8d961b7..8f8c009 100644
--- a/Doc/library/statistics.rst
+++ b/Doc/library/statistics.rst
@@ -471,9 +471,11 @@
:class:`NormalDist` objects
===========================
-A :class:`NormalDist` is a a composite class that treats the mean and standard
-deviation of data measurements as a single entity. It is a tool for creating
-and manipulating normal distributions of a random variable.
+:class:`NormalDist` is a tool for creating and manipulating normal
+distributions of a `random variable
+<http://www.stat.yale.edu/Courses/1997-98/101/ranvar.htm>`_. It is a
+composite class that treats the mean and standard deviation of data
+measurements as a single entity.
Normal distributions arise from the `Central Limit Theorem
<https://en.wikipedia.org/wiki/Central_limit_theorem>`_ and have a wide range
@@ -530,7 +532,7 @@
Using a `probability density function (pdf)
<https://en.wikipedia.org/wiki/Probability_density_function>`_,
- compute the relative likelihood that a random sample *X* will be near
+ compute the relative likelihood that a random variable *X* will be near
the given value *x*. Mathematically, it is the ratio ``P(x <= X <
x+dx) / dx``.
@@ -544,7 +546,7 @@
Using a `cumulative distribution function (cdf)
<https://en.wikipedia.org/wiki/Cumulative_distribution_function>`_,
- compute the probability that a random sample *X* will be less than or
+ compute the probability that a random variable *X* will be less than or
equal to *x*. Mathematically, it is written ``P(X <= x)``.
Instances of :class:`NormalDist` support addition, subtraction,