  We present a parameterization of the statistical rate function, f, for 20
superallowed 0+-to-0+ nuclear beta transitions between T=1 analog states, and
for 18 superallowed "mirror" transitions between analog T=1/2 states. All these
transitions are of interest in the determination of V_{ud}. Although most of
the transition Q_{EC} values have been measured, their precision will
undoubtedly be improved in future. Our parameterization allows a user to easily
calculate the corresponding new f value to high precision (+/-0.01%) without
complicated computing.
