SITEMAP ABOUT
MiC Quality

SIX SIGMA GLOSSARY

  PROCESS IMPROVEMENT AND SIX SIGMA
ONLINE COURSES FREE TRIAL SIX SIGMA FAQ BROCHURES LICENSES ENROLL
GLOSSARY
:: Online Courses
:: Free Trial
:: Six Sigma
>> Glossary
>> Calculators
>> Reference Tables
>> Book Reviews
>> Black Belt ASQ
:: FAQ
:: Brochures
:: Licenses
:: Discounts
 
Welcome to MiC Quality Six Sigma Resources
Online Course Instructor
Glen Netherwood
MiC Quality
Online Learning
:: Home ::Six Sigma ::SIX SIGMA GLOSSARY: Wilcoxon Signed Tank Test :: CURRENT STUDENTS LOGIN

[SIX SIGMA GLOSSARY ALPHABETICAL INDEX] [SIX SIGMA GLOSSARY INDEX OF TOPICS]

Wilcoxon Signed Rank Test
 

The Wilcoxon Signed Rank Test is a nonparametric equivalent of the one sample t-test. It tests the hypothesis:

H0 the mean equals zero
H1 the mean [is less than/greater than/not equal to] zero

The test involves:

  • sort the values into order of their absolute magnitude (ignoring the signs) and allocate ranks
  • calculate the sum the ranks of the data values are positive (S+)

An example would be:

Rank
1
2
3
4
5
6
Data Value
-1.0
-2.0
2.5
3.0
3.0
3.5

If the mean is non-zero the positive values will be clustered at one end or other of the ordered data set and S+ and S- will be very different.

For the example S+ = 3 + 4 + 5 + 6 = 18

For small data sets values the critical value is found from published tables. Because the sum of the ranks must be an integer, it is not usually possible to find the exact critical value:

hypothesis 1
hypothesis 2 where
hypothesis 3

For larger data sets the z-statistic can be found from:

wilcoxon signed rank

This gives the upper tail test (the mean is less than zero). For the lower tail test, use the sum S+ and for the two tailed test use both, remembering to use the table value twice.

The p-value can be calculated using normal distribution tables.

 

MiC Quality offers online courses that can help you prepare for the American Society for Quality (ASQ) Certified Six Sigma Black Belt examination.

Try out our courses by taking the first module of the Primer in Statistics free of charge.

  Enroll Now
[SIX SIGMA GLOSSARY ALPHABETICAL INDEX] [SIX SIGMA GLOSSARY INDEX OF TOPICS] [Top]

MiC Quality Courses
:: Six Sigma Primer
:: Primer in Statistics
:: Advanced Statistics
:: Statistical Process Control SPC
:: Advanced SPC
:: Design of Experiments
:: Advanced DOE
:: Measurement Systems Analysis MSA/ Gage R&R
   
Primer in Statistics
FREE First Module
"Introduction to Statistics"

PDF

Primer in Statistics
FREE Reference Booklet

FREE Excel Primer
   
Learn More



 
Copyright 1998-2014 MiC Quality Legal Notices and Privacy Policy