An OSCE that runs across multiple sittings exposes its stations to the candidates who sit first. Quarantine is the procedure that stops them telling the candidates who sit next: the later cohort is on site and without devices before the earlier cohort is released. Station security is the rest of it: numbered packs, counted mark sheets, doorway sheets that come down, and a rule for reusing stations. The evidence indicates that leakage occurs and that its effect on marks is small and hard to detect. Both halves matter.
What leaks, and does it matter?
Two studies looked directly. At one US school, six administrations of a skills OSCE were analyzed for rising scores across sittings and across each 8.5-hour day. No significant rise appeared. The authors concluded that sharing information did not change scores. At a UK school, 255 third-year students sat a 15-station OSCE on three sites over two days. Students then reported collusion on an electronic discussion board. Most contributors said they had received prior knowledge, or knew of others who had. None admitted passing it on. Day-two marks were not significantly higher overall. One pathology item showed a clear pattern: 82 students on day two gave the same wrong diagnosis.
The lesson is uncomfortable. Marks do not show whether leakage happened. A school that checks day-two scores, finds no rise and declares the exam secure has tested the wrong thing. Leakage shows up in a single item, in a discussion board, and in candidates' sense that the exam was unfair. The procedure has to prevent it, because the numbers will not detect it.
How does quarantine work?
The AMEE guide on OSCE organization states: keep the earlier cohort until the later cohort has arrived, with no phones. The procedure has five parts.
- The later cohort registers first. They hand in phones and devices and enter the holding room before the earlier cohort's last bell. The run-sheet places this at the changeover.
- The earlier cohort walks straight to quarantine. Marshals take them from the last station to the quarantine room by a route that does not pass the holding room. The venue page covers the rooms.
- Quarantine is staffed and supplied. Water, food, toilets with an escort, and a member of staff at the door. Candidates get their devices back when they leave, not before.
- Release is a single event. The whole cohort leaves when the later cohort is inside the circuit. Nobody leaves early for a non-medical reason.
- A candidate who must leave is recorded. Illness, a child, a flight: the coordinator records the time, and the incident log notes that the candidate left before release. If the school's regulations allow a sanction for contact with a later cohort, the briefing stated as much.
Quarantine works across sessions in a day. It cannot work overnight. A two-day exam depends on the other controls.
How are stations kept secure on the day?
The AMEE guide's troubleshooting list includes instructions and mark sheets that have been removed. The controls are counts.
Electronic marking removes the mark-sheet counts and replaces them with an access rule: an examiner sees only their own station at their own event. The marking page covers the rest.
Can stations be reused?
Yes, with the procedure above. A ten-station OSCE at one school reused six stations over the years, with 191 and then 236 candidates. The test's characteristics were equivalent in both years, and the reliability coefficient stayed above 0.70. The authors concluded that, with careful security measures, high-stakes OSCEs may use the same stations. The station bank page outlines how a bank tracks exposure so that the decision to reuse is recorded.
What about a two-day exam?
Overnight, there is no quarantine. The choice is between three positions, and the circuit planning page weighs them. Run the same stations and accept the exposure, with the comparability check and the knowledge that it detects little. Run different stations on each day and equate the forms. Or add a parallel circuit and finish in one day. The UK study above ran over two days, and its authors' point stands: what the school could see afterward was the discussion board, not the marks.
The social-media rule
Candidates talk about the exam within minutes of release. The briefing states the rule: no station content is described, posted or messaged until the exam board has released the stations, and the school's fitness-to-practice regulations apply. The rule is not a control. It is a record that the candidates were told, which the regulations page needs if a case follows.
Frequently asked questions
What is quarantine in an OSCE?
Holding the candidates who have finished until the next cohort is on site and without devices. It stops the first cohort from telling the second what the stations are. It works within a day, not overnight.
Does information sharing change OSCE scores?
Studies found no significant rise in overall marks across sittings or days. One study found a clear pattern in a single item and student reports of collusion. Marks do not show leakage. The procedure has to prevent it.
Can OSCE stations be reused the next year?
Yes, with careful security. One school reused six of ten stations, spaced a year apart, and found equivalent test characteristics and reliability above 0.70 in both years. Track exposure in the station bank.
What should be counted at an OSCE station?
Mark sheets and candidate instructions are out at registration and in at every changeover. Doorway sheets come down at the changeover. A missing sheet is reported before the examiner leaves.
Can candidates leave the OSCE quarantine early?
Only for a medical or urgent reason, recorded by the coordinator with the time. The candidate briefing states that contact with a later cohort is a conduct matter under the school's regulations.