Ninety-six nylon pairs were prepared, including red, yellow, green, and blue standards, each at two lightness levels with CIE94 Delta E units ranging from 0.15 to 4.01. Visual assessments of acceptability were carried out by 21 females. Logistic regression compared visual results to four color-difference equations, CIELAB, CMC, CIE94, and CIEDE2000. It was found that CMC most closely represented judgments of average observers. (c) 2005 Wiley Periodicals, Inc.