2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/163526q-Expectation value of a physical quantity is widely used in nonextensive statistical mechanics. Here, it is shown that the q-expectation value is not stable under small deformations of a probability distribution function, in general, whereas the ordinary expectation value is always stable.8 pages, no figuresStatistical Mechanicstext