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SNPPFName:
For = 0, the skew-normal reduces to a normal distribution. As goes to , the skew-normal tends to the half-normal distribution. The skew-normal percent point function is computed by numerically inverting the skew-normal cumulative distribution function (which in turn is computed by numerically integrating the skew-normal density function). The standard skew-normal distribution can be generalized with location and scale parameters.
<SUBSET/EXCEPT/FOR qualification> where <p> is a variable or a parameter in the range (0,1); <lambda> is a number of parameter that specifies the value of the shape parameter; <loc> is an optional number or parameter that specifies the value of the location parameter; <scale> is an optional positive number or parameter that specifies the value of the scale parameter; <y> is a variable or a parameter (depending on what <x> is) where the computed skew-normal ppf value is stored; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
LET A = SNPPF(A1,LAMBDA) LET X = SNPPF(P1,0.5)
"Continuous Univariate Distributions: Volume I", Second Edition, Johnson, Kotz, and Balakrishnan, Wiley, 1994, p. 454.
MULTIPLOT 2 2 MULTIPLOT CORNER COORDINATES 0 0 100 100 TITLE SKEW-NORMAL: LAMBDA = 0 PLOT SNPPF(P,0) FOR P = 0.01 0.01 0.99 TITLE SKEW-NORMAL: LAMBDA = 1 PLOT SNPPF(P,1) FOR P = 0.01 0.01 0.99 TITLE SKEW-NORMAL: LAMBDA = 5 PLOT SNPPF(P,5) FOR P = 0.01 0.01 0.99 TITLE SKEW-NORMAL: LAMBDA = 10 PLOT SNPPF(P,10) FOR P = 0.01 0.01 0.99 END OF MULTIPLOT
Date created: 2/3/2004 |