The RIT-DuPont dataset has been used extensively for formula development and testing since its inception during the 1980's, for example, in the development of CIE94 and CIEDE2000. The dataset was published as 156 color-tolerances, T-50, along specific vector directions about 19 color centers. Probit analysis was used to transform judgments of 958 color-difference pairs by 50 observers to these 156 tolerances. For most statistical significance testing, the number of samples determines the confidence limits. Thus, there was an interest in publishing the individual color-difference pair visual and colorimetric data to improve the precision of significance testing. From these 958 pairs, 828 pairs had determinable visual differences. The others had either excessive visual uncertainty or had unanimous visual judgments such that visual differences were undefined. In addition, a method was devised to assign visual uncertainty to each of these pairs using the principles of maximum likelihood and the T-50 values. Comparisons were made between the T-50 and individual color-difference pair data both including and omitting uncertainty weightings. The weighted dataset was found to be equivalent to the T-50 tolerances. (C) 2009 Wiley Periodicals, Inc. Col Res Appl, 35, 274-283, 2010; Published online 10 November 2009 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20548