  In this work we discuss the measurement protocols for indirect determination
of the isothermal entropy change associated with first order phase transitions
in caloric materials. The magneto- structural phase transitions giving rise to
giant magnetocaloric effects in Cu-doped MnAs and FeRh are used as case studies
to exemplify how badly designed protocols may affect isothermal measure- ments
and lead to incorrect entropy change estimations. Isothermal measurement
protocols which allow correct assessment of the entropy change around first
order phase transitions in both direct and inverse cases are presented.
