We introduce a family of convex (concave) functions called sup (inf) of powers, which areused as generator functions for a special type of quasi-arithmetic means. Using thesemeans, we generalize the large deviation result on self-normalized statistics that wasobtained in the homogeneous case by [Q.-M. Shao, Self-normalized large deviations.Ann. Probab. 25 (1997) 285–328]. Furthermore, in thehomogenous case, we derive the Bahadur exact slope for tests using self-normalizedstatistics.