I've been trying to find detailed percentiles for SF-36 PF scores for the adult population, but have been unable to so far. But I have come across some helpful percentiles for the six minute walking distance test, for healthy adults. In the PACE Trial, the distances walked in the 6MWD test, post-treatment, for the therapy groups was as follows: GET = 379m CBT = 354m I've found a study that gives the 10th percentile of 'normal' men and women... The 6-min walk distance in healthy subjects: reference standards from seven countries C. Casanova et al. doi: 10.1183/09031936.00194909 ERJ January 1, 2011 vol. 37 no. 1 150-156 June 4, 2010, http://erj.ersjournals.com/content/37/1/150.full 10th percentile for 'normal' men (age 50-59) = ~475m (approximation based on graph - precise data not given) 10th percentile for 'normal' women (age 50-59) = ~475m (approximation based on graph - precise data not given) And there's another paper that shows the 5th percentiles for healthy men and women... Reference Equations for the Six-Minute Walk in Healthy Adults PAUL L. ENRIGHT and DUANE L. SHERRILL AM J RESPIR CRIT CARE MED 1998;158:1384–1387. http://ajrccm.atsjournals.org/content/158/5/1384.full.pdf 5th percentile for healthy men = 399m (n = 117, median age = 59.5) 5th percentile for healthy women = 310m (n = 173, median age = 62) So I think the post-treatment mean 6MWDT distances in the PACE Trial, are roughly at about the 5th percentile of the healthy adult population. (i.e. within the lowest performing 5% of the healthy population.) I can't find any data for the whole population, as opposed to healthy adults only.