This paper outlines a method for assessing trait economic impacts, at the level of the individual animals considered in selection, for traits where the economic value changes across the range of the trait. Results are compared with those from linear methods for price patterns that are common for traits, such as beef carcase fat depth, weight and marbling score, which affect market acceptability and preference. Some important deviations from linearity were seen in the change in index that occurs with change in estimated breeding value (EBV) for these traits. The deviations were most evident at the extremes of the EBV range, which could affect the animals selected. Simple extensions of the method are also suited for use in mate selection and other important areas where non-linearity is encountered.