Anchor-based estimates are often made by comparing the patient-reported outcome score with a global change score. Investigators sometimes apply this approach retrospectively, using a global scale that was applied in the study for another purpose (as used by Dr Kocks and colleagues on our data). That is a mistake. Global scales are designed for a specific purpose, in our case to test whether the CAT could measure recovery after a specific period (14 days). Our scales were not worded to identify minimum beneficial change; furthermore, a change judged worthwhile at 14 days may be different from one at 28 days.