diff -r cdb7f31a7e10 Doc/library/statistics.rst
--- a/Doc/library/statistics.rst	Sat Feb 08 19:58:04 2014 +1000
+++ b/Doc/library/statistics.rst	Sat Feb 08 20:02:24 2014 +1000
@@ -271,13 +271,13 @@
 .. function:: pvariance(data, mu=None)
 
    Return the population variance of *data*, a non-empty iterable of real-valued
-   numbers.  Variance, or second moment about the mean, is a measure of the
-   variability (spread or dispersion) of data.  A large variance indicates that
-   the data is spread out; a small variance indicates it is clustered closely
-   around the mean.
+   numbers representing the entire population.  Variance, or second moment about
+   the mean, is a measure of the variability (spread or dispersion) of data.  A
+   large variance indicates that the data is spread out; a small variance
+   indicates it is clustered closely around the mean.
 
-   If the optional second argument *mu* is given, it should be the mean of
-   *data*.  If it is missing or ``None`` (the default), the mean is
+   If the optional second argument *mu* is given, it should be the population
+   mean μ of *data*.  If it is missing or ``None`` (the default), the mean is
    automatically calculated.
 
    Use this function to calculate the variance from the entire population.  To
@@ -346,13 +346,13 @@
 .. function:: variance(data, xbar=None)
 
    Return the sample variance of *data*, an iterable of at least two real-valued
-   numbers.  Variance, or second moment about the mean, is a measure of the
-   variability (spread or dispersion) of data.  A large variance indicates that
-   the data is spread out; a small variance indicates it is clustered closely
-   around the mean.
+   numbers representing a sample from the larger population.  Variance, or
+   second moment about the mean, is a measure of the variability (spread or
+   dispersion) of data.  A large variance indicates that the data is spread out;
+   a small variance indicates it is clustered closely around the mean.
 
    If the optional second argument *xbar* is given, it should be the mean of
-   *data*.  If it is missing or ``None`` (the default), the mean is
+   the sample *data*.  If it is missing or ``None`` (the default), the mean is
    automatically calculated.
 
    Use this function when your data is a sample from a population. To calculate
@@ -414,5 +414,5 @@
    Subclass of :exc:`ValueError` for statistics-related exceptions.
 
 ..
-   # This modelines must appear within the last ten lines of the file.
+   # This modeline must appear within the last ten lines of the file.
    kate: indent-width 3; remove-trailing-space on; replace-tabs on; encoding utf-8;