

 :: Tukey lambda PPCC Plot  Free Statistics Software (Calculator) :: 


All rights reserved. The noncommercial (academic) use of this software is free of charge. The only thing that is asked in return is to cite this software when results are used in publications.
This free online software (calculator) computes the Tukey lambda PPCC Plot that is used to identify whether a distribution is short or long tailed (only applies to symmetric distributions). In addition it can indicate several common distributions. Specifically,
 lambda = 1: distribution is approximately Cauchy
 lambda = 0: distribution is exactly logistic
 lambda = 0.14: distribution is approximately normal
 lambda = 0.5: distribution is Ushaped
 lambda = 1: distribution is exactly uniform

If the Tukey Lambda PPCC plot gives a maximum value near 0.14, we can reasonably conclude that the normal distribution is a good model for the data. If the maximum value is less than 0.14, a
longtailed distribution such as the double exponential or logistic would be a better choice. If the maximum value is near 1, this implies the selection of very longtailed distribution, such as the Cauchy. If the maximum value is greater than 0.14, this implies a shorttailed distribution such as the Beta or uniform.
source: NIST/SEMATECH eHandbook of Statistical Methods, http://www.itl.nist.gov/div898/handbook/, 20061003.
Enter (or paste) your data delimited by hard returns.
Source code of R module  

Cite this software as:  Wessa P., (2021), Tukey lambda PPCC Plot (v1.0.4) in Free Statistics Software (v1.2.1), Office for Research Development and Education, URL http://www.wessa.net/rwasp_tukeylambda.wasp/   The R code is based on :   NIST/SEMATECH eHandbook of Statistical Methods, http://www.itl.nist.gov/div898/handbook/, 20061003.              

To cite Wessa.net in publications use: Wessa, P. (2024), Free Statistics Software, Office for Research Development and Education, version 1.2.1, URL https://www.wessa.net/
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