RT Journal Article SR Electronic T1 The Hawthorne effect in measurements of hand hygiene compliance: a definite problem, but also an opportunity JF BMJ Quality & Safety JO BMJ Qual Saf FD BMJ Publishing Group Ltd SP 965 OP 967 DO 10.1136/bmjqs-2014-003507 VO 23 IS 12 A1 Sarah Haessler YR 2014 UL http://qualitysafety.bmj.com/content/23/12/965.abstract AB