The 4-point importance scale used in the self-explicated priors in ACA has been a focus of some debate. Specifically, it has been suggested that the 4-point scale is too coarse. William McLauchlan studied the effects of using different scales in ACA, and presented the results via this paper at the 1991 Sawtooth Software Conference. In cooperation with Sawtooth Software, three versions of ACA were created and tested: 1) ACA Version 3.0, 2) ACA Version 3.0 with a 9-point importance scale, 3) Analog ACA, which elicited prior utilities using a finely-graded analog scale. McLauchlan found no significant differences in predictability of hold-out concepts among the three versions of ACA. However, the analog version of ACA took significantly more time for respondents to complete.