Those involved in research projects often need to take measurements of some kind, and usually, the more accurate the better – leading to the question ‘Can any measurement ever be taken without some margin of error?’ As an example, see the work of Professor P R Evans, writing in the Wader Study Group Bulletin, (69, Special Issue):97-98, 1993. Correct measurement of the wing-length of waders
“It has been drawn to my attention that there is some confusion as to the most reliable method of measuring the wing-length of waders, i.e. the method that minimizes differences in measurements obtained from the same bird by different workers on the same occasion, or by the same worker on different occasions.”
Also see: Curiosity: “ZERO margin of error”?