50 healty normosmic students obtained odor thresholds for butanol using the Sniffin` Sticks test (SnS), as well as the method of limits (ML) in ascending and descending order. The procedures were repeated about 2 weeks later. For each session and method the performance time was taken and subjects rated the pleasantness of the odor and the strain required by the task using a category anchored Visual Analogue Scale. For all subjects plausible thresholds
could be obtained by the SnS procedure and by the ascending ML. For 22 out of 50 subjects, however, thresholds could not be obtained by the descending ML. Further analysis of the data revealed worse performance and significantly lower retest-reliabilities for those subjects in the ascending ML and the SnS-procedure as well.