[Python-checkins] cpython (3.6): Add another example to the recipes section of the random docs

Thu Nov 17 01:56:43 EST 2016

https://hg.python.org/cpython/rev/5d216c21f01f
changeset: 105170:5d216c21f01f
branch: 3.6
parent: 105168:331ac810495f
user: Raymond Hettinger <python at rcn.com>
date: Wed Nov 16 22:56:11 2016 -0800
summary:
 Add another example to the recipes section of the random docs
files:
 Doc/library/random.rst | 26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/Doc/library/random.rst b/Doc/library/random.rst
--- a/Doc/library/random.rst
+++ b/Doc/library/random.rst
@@ -372,3 +372,29 @@
 print(f'The sample mean of {mean(data):.1f} has a 90% confidence '
 f'interval from {means[1]:.1f} to {means[-2]:.1f}')
 
+Example of a `resampling permutation test
+<https://en.wikipedia.org/wiki/Resampling_(statistics)#Permutation_tests>`_
+to determine the statistical significance or `p-value
+<https://en.wikipedia.org/wiki/P-value>`_ of an observed difference
+between the effects of a drug versus a placebo::
+
+ # Example from "Statistics is Easy" by Dennis Shasha and Manda Wilson
+ from statistics import mean
+ from random import shuffle
+
+ drug = [54, 73, 53, 70, 73, 68, 52, 65, 65]
+ placebo = [54, 51, 58, 44, 55, 52, 42, 47, 58, 46]
+ observed_diff = mean(drug) - mean(placebo)
+
+ n = 10000
+ count = 0
+ combined = drug + placebo
+ for i in range(n):
+ shuffle(combined)
+ new_diff = mean(combined[:len(drug)]) - mean(combined[len(drug):])
+ count += (new_diff >= observed_diff)
+
+ print(f'{n} label reshufflings produced only {count} instances with a difference')
+ print(f'at least as extreme as the observed difference of {observed_diff:.1f}.')
+ print(f'The one-sided p-value of {count / n:.4f} leads us to reject the null')
+ print(f'hypothesis that the observed difference occurred due to chance.')
-- 
Repository URL: https://hg.python.org/cpython
