PACE used wrong data to define 'normal' fatigue We've already shown how the PACE definition of 'normal' for SF36 function is wrong, but it's been harder to pin down the problems with the Fatigue defintion. I'm pretty sure there I've now found data showing PACE used the wrong fatigue data to set its norms, because their 'normative' sample was very sick. Since I failed to excite anyone with my previous post, I'm having one last go at explaining this: One point of explanation. The Cella 2010 paper that was used for PACE's definition of 18 as 'normal' used a subset of a sample of 15,000 patients published in 1994. However, we know that the mean for Cella subsample was 14.2, higher than the mean of the original sample of 13.8 (a statistically significant difference) so we can conclude that the Cella sample is at least as fatigued as the original sample, hence the figures above should apply to the Cella data too. My original post has the details. OK, I've done my best, if no one's interested I promise I won't mention it again.