Width

The width of a statistical distribution is not unambiguously defined in the literature, although the term is frequently used by physicists. Sometimes, width is used as a synonym for standard deviation, i.e. the positive square root of the variance . More correctly, for empirical distributions like histograms obtained from experiment the width is frequently used as an abbreviation for full width at half maximum. The latter is a relevant parameter of the Breit-Wigner ( or Lorentz or Cauchy) distribution.