Table 1

Summary of quantitative data collection methods by system

	System	Definition against which reliability was measured	Method of data collection	Sample: total and by organisation
1	Clinical information availability in hospital outpatient clinics	Core data set of information required in a typical surgical outpatient clinic^*, as agreed by surgeons. 100% reliability defined as all patients having all required information available at the time of their appointment	Form completed by surgeons in clinic about missing information, including perceived risks and the action taken as a result	Total: 1161 outpatient consultations A: 411 E: 423 G: 327
2	Prescribing for hospital inpatients	A published, validated, definition of a prescribing error was used15 100% reliability defined as all medication orders being error free	Prescribing errors in newly written inpatient and discharge medication orders identified and recorded by ward pharmacists. Medical admissions and surgical wards were studied. Clinical importance assessed using a validated method	Total: 6605 medication orders A: 2689 B: 1812 C: 2104
3	Equipment availability in the operating theatre	100% reliability defined as all operations having the required equipment available and in working condition at the time it was needed	Theatre staff collected data on equipment failures in trauma and orthopaedics, general surgery and paediatric operating theatres, including perceived delays to operation and threats to patient safety	Total: 490 operations studied A:258 D:67 F:165
4	Systems for inserting peripheral intravenous lines	100% reliability defined as having all equipment needed to insert the intravenous line available to staff at the time required	Staff performing cannulations in accident and emergency departments and acute medical wards completed data collection forms after each procedure, including perceived threats to patient safety	Total: 350 intravenous line insertions studied A:76 D:62 F:212

↵* Past medical history; referral or other specialty letter; discharge summary; current medication; allergies; radiology/imaging results; diagnostic test results; procedure notes/anaesthetic record; electrocardiogram report; blood laboratory results; outpatient medical record/last clinic letter.