On the alternative to the Weibull function

It is pointed out that the distribution introduced by Neville and Kennedy [Neville DJ, Kennedy JB. An alternative to the Weibull function for some cases. J Mech Des 1991;113:195–9] (for modeling fracture toughness and fracture stress) is contained by at least two known families of distributions. Some elementary statistical properties of these families are discussed. Six data sets on fracture roughness are used to demonstrate that these families are much better models for fracture roughness than the one introduced by Neville [Neville DJ, Kennedy JB. An alternative to the Weibull function for some cases. J Mech Des 1991;113:195–9].