Table 2. Sample of a matched pair of items.

Item-writing flaw	IWF3: Clues to the right answer (pairs of options) Single pair of options (two options are perceived as a pair by candidates, who limit their guess to the pair)
Flawed	Which one of the following is the best way of confirming correct placement of the endotracheal tube? A.Fogging on plastic tubing B.Visualisation of symmetrical chest wall rise and fall C. Expired concentrations of oxygen D. Expired concentrations of carbon dioxide* E.Equal air entry on chest auscultation
Unflawed	Which one of the following is the best way of confirming correct placement of the endotracheal tube? A.Fogging on plastic tubing B.Visualisation of symmetrical chest wall rise and fall C.Direct visualisation between the vocal cords D.Expired concentrations of carbon dioxide* E.Equal air entry on chest auscultation