Researchers have employed the Juster Scale to collect purchase probability data with notable success. Reviewing the Juster Scale studies, however, has revealed that there is considerable variation in its per¬formance. Some of these variations appeared to be caused by the context in which the Juster Scale has been presented to respondents. This paper discusses three factors that influence the context of the Juster Scale and reports the results of a study that attempted to standardise its contextual requirements. The results substantiate further the Juster Scale's satisfactory performance in collecting purchase probability data.