Intrinsic unsharpness and approximate repeatability of quantum   measurements
  The intrinsic unsharpness of a quantum observable is studied by introducing the notion of resolution width. This quantification of accuracy is shown to be closely connected with the possibility of making approximately repeatable measurements. As a case study, the intrinsic unsharpness and approximate repeatability of position and momentum measurements are examined in detail. 
C. Carmeli, T. Heinonen, A. Toigo