A systematic study of the effect of fragment-fragment interaction, quantum
statistics, gamma-feeding, and collective flow is made in the extraction of
the nuclear temperature from the double ratio of the isotopic yields in th
e statistical model of one-step (prompt) multifragmentation. Temperature is
also extracted from the isotope yield ratios generated in the sequential b
inary-decay model. Comparison of the thermodynamic temperature with the ext
racted temperatures for different isotope ratios show some anomaly in both
models which is discussed in the context of experimentally measured caloric
curves. [S0556-2813(99)06002-1].