The sign of lattice and spin entropy change in the giant magnetocaloric materials with negative lattice expansions

•Magnetocaloric materials often show negative lattice expansion.•The sign of lattice (ΔSLatt) and spin entropy change (ΔSSpin) remains debate.•The sign of ΔSLatt and ΔSSpin is clarified.•For MM’X alloys, heat flow results prove the same signs of ΔSLatt and ΔSpin.•For La(Fe,Si)13, NRIXS evidences the same signs of ΔSLatt and ΔSSpin.