Questions on Uncertainties in Parton Distributions
  A discussion is presented of the manner in which uncertainties in parton distributions and related quantities are determined. One of the central problems is the criteria used to judge what variation of the parameters describing a set of partons is acceptable within the context of a global fit. Various ways of addressing this question are outlined. 
R.S. Thorne, H. Boettcher, A.M. Cooper-Sarkar, B. Reisert, V.   Shekelyan, W.J. Stirling, D.R. Stump, A.Vogt