Probability plotting positions/estimators Lecture
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All plotting positions return crude estimates of the unknown probabilities associated the studied events.  The principal estimators are presented in the Table below.
Name Probability estimators
Adamowski (1981) [3] i - 0.25
n + 0.25
APL [1] i - 0.35
n
Beard (1943) [1-3]  i - 0.3175 
n + 0.38
Blom (1958) [1-3]  i - 3/8 
n + 1/4
California (1923) [2-3]  i 
n
Chegodayev (1955) [2-3] i - 0.3
n + 0.4
Cunnane (1978) [1-3] i - 0.4
n + 0.2
Filliben (1975) i - 0.3175
n + 0.25
Gringorten (1963) [1, 2] i - 0.44
n + 0.12
Hazen (1914) [1-3] i - 0.5
n
Nguyen et al (1989) [1]       i -0.42      
n + 0.3γ + 0.05
Tukey (1974) [2] i - 1/3
n + 1/3
Weibull (1939) [1-3]   i  
n + 1

References

  1. A Shabri, A comparison of plotting formulas for the Pearson Type III distribution, Jurnal Teknologi (Universiti Teknologi Malaysia), June 2002, 36(C), 61–74.
  2. AS Yahaya, CS Yee, NA Ramli and F Ahmad, Determination of the best probability plotting position for predicting parameters of the Weibull distribution, International Journal of Applied Science and Technology, March 2012, 2(3), 106-111.
  3. Statistical techniques for data analysis, Chapter 4 in SK Jain and VP Singh, Water Resources Systems Planning and Management (Developments in Water Science), Elsevier Science, Amsterdam, 2003.  ISBN 0-444-51429-5.
Created by John Summerscales on 02-Apr-2016 and updated on 02-Apr-2016 15:09. Terms and conditions. Errors and omissions. Corrections.