Table 1.

Comparison of the methods with respect to their required procedures and the assumptions underlying scale estimation in MLDS and MLCM.

	Asymmetric matching	MLDS	MLCM
Procedure
Comparison	Across-context	Within-context	Within- and across-context
Judgment	Equality	Difference between intervals	Simple difference
Task	Adjust until equal	Triad comparison	Paired comparison
Outcome	Matches in unit of interest	Perceptual scales	Perceptual scales
Assumptions
Noise	–	Additive noise, separate for each scale	Single additive noise for all scales
Scale minimum	–	Each scale at zero	Reference scale at zero, others estimated from data relative to reference
Scale maximum	–	Inverse of estimated noise for each scale	Inverse of estimated noise for reference scale, others estimated from data relative to reference