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Estimation of Generalized Extreme
Value Distribution:
Maximum-likelihood Method
Case study:
Precipitation Annual Maximum Series
Burke Garden, VA
Ako Heidari
Extreme Value Theory
 Branch Of Statistics
 Dealing With The Extreme Deviations
 From The Median Of Probability Distributions
 Try To Assess
 The Probability Of Events That Are More Extreme Than Any
Previously Observed
 Based On Given Ordered Sample
Paradigm:
 Dealing With AMS
 Model Development
 Idealized
 Model Wastage
GEV Applications:
 Used In Many Disciplines
 Specially In Hydrology And Meteorology
 Wind Engineering
 Management Strategy
 Biomedical Data Process
 Thermodynamic Of Earthquake
GEV Distribution:
 family of continuous probability distributions
 developed within extreme value theory
 unites the Gumbel, Fr辿chet and Weibull distributions
 AKA: type I, II and III
 F(x;亮,,両)=exp{[1+両(
モ

)]}

1

    is the location parameter
  > 0 the scale parameter and 両   the shape parameter.
Clim-final
Why GEV?
Climate
Change
Intensification
In The
Hydrologic
Cycle
Extreme
Flood And
Drought
Different Method:
 Method Of Moments
 Maximum Likelihood
 Likelihood Function:     ;   =   ; 
 Is Unique In Adaptability To Model Changing
R packages for extreme
values
Ismev package
extReme
Fetdvcommand
Functions for extreme value distributions
Extends simulation, distribution, quantile and density
functions
 univariate and multivariate data
 parametric extreme value distributions
 A. G. Stephenson. evd: Extreme Value Distributions. R News, 2(2):31-32, June 2002. URL: http://CRAN.R-project.org/doc/Rnews/
Package: evd
Function: fgev
 Maximum-likelihood Fitting
 Of The Generalized Extreme Value Distribution
Data:
T-S1: 1896-1949 T-S2: 1950-2000
Results:
T-S1
Results:
T-S2
Results:
T-S 1
Location: 1.95
scale :0.52
shape :-0.12
T-S 2
Location: 1.99
scale :0.57
shape :-0.06
Results:
Standard
Location: 0.080
scale :0.058
shape :0.10
Error
Location: 0.086
scale :0.06
shape :0.08
Answer:
 1~ 1, 裡1
 2~ 2, 裡2
 (1 2) (裡1 + 2)1(1 2)~ 
2
Summary
 Question: Estimating Extreme Values For A Specific Time Series
 Methodology: Maximum Likelihood, Generalized Extreme Value
 Answer: No Significant Change

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