PDF Function :: SAS(R) 9.3 Functions and CALL Routines: …
Details. The PDF function for the Wald distribution returns the probability density function of a Wald distribution, with shape parameter λ, which is evaluated at the value x . The equation follows: f x ( x ) = [ λ 2 π x 3 ] 1 / 2 exp. . { − λ 2 μ 2 x ( x − μ ) 2 }, x > 0.