title: [Standard ballpoint pens disappear from the coats with a half-life of nine days].
abstract: Ballpoint pens are important tools for the daily work of the physicians. However, a practical challenge seems to be that they disappear just when one needs them most. We call this the ballpoint pen paradox. We have studied the fate of 60 ballpoint pens in an outpatient clinical setting. Five physicians, five nurses and five medical secretaries were equipped with four barcode-tagged ballpoint pens. During follow-ups, we systematically searched the participants' coat and the department for the barcode-tagged ballpoint pens. We illustrated the migration of the ballpoint pens using a diagram and tested fit of linear and exponential trend line. The ballpoint pens displayed a tremendous migration in the department. Disappearance from the coat was exponentially with a half-life of 9 days - only 23% were left after 18 days. Disappearance from the department was linear with a 3% loss per day - only 42% were left after 18 days. Ballpoint pens have a high migration and turnover rate. The fate is unknown for a great amount of ballpoint pens. They are treated carelessly, which finally results in waste of time and resources. It may be that the ballpoint pen paradox can be diminished by phasing out ballpoint pens of low quality.
  
  
  BACKGROUND
  not relevant.
  
  
  BACKGROUND
  not relevant.
authors.affiliation: Øjenafdelingen, Roskilde Sygehus, K øgevej 9-13, 4000 Roskilde. ysubhi@gmail.com.
authors.forename: Yousif
authors.initials: Y
authors.lastname: Subhi
authors.forename: Troels
authors.initials: T
authors.lastname: Brynskov
mesh_terms: D003020:Clothing; D004865:Equipment and Supplies, Hospital / Q000600:supply & distribution*; D005500:Follow-Up Studies; D006801:Humans; D008502:Medical Secretaries; D009726:Nurses; D010044:Outpatient Clinics, Hospital; D010820:Physicians