---
title: "Red flags, critical errors and must-pass stations: writing the policy"
description: "How to write an OSCE critical-error policy: what counts as a critical item, how it differs from a must-pass station, and who approves it."
canonical: https://studydrome.com/docs/osce/design/critical-errors-and-must-pass/
updated: 2026-09-27
---

# Red flags, critical errors and must-pass stations: writing the policy

How to write an OSCE critical-error policy: what counts as a critical item, how it differs from a must-pass station, and who approves it.

A critical error is an action or omission that results in a station failure regardless of the candidate's total. A must-pass station is a station that fails the exam regardless of the aggregate. Both are policy decisions. They are written before the exam, approved by the assessment committee, published to candidates and recorded on the marking scheme, so that an examiner applies them and a board defends them.

## Why this needs a policy and not a habit

Most schools have at least one item that "should fail the station". Few have written down what makes an item critical, who decided, and what the candidate was told. That gap shows at appeal. A candidate who scored 80 percent on a station and failed it because of one unticked box will ask for the rule. The rule must exist in writing and be dated before the exam.

The rule also has to be scarce. A scheme with six critical items is a scheme where the checklist total means nothing. The policy sets the bar high so that a critical item stays rare and defensible.

## What are the terms?

| Term | What it means | Effect | Set where |
| --- | --- | --- | --- |
| Critical item | A checklist item that a candidate must score at or above a set level | Fails that station only | Marking scheme, per station |
| Critical error or red flag | The behavior a critical item detects: harm, danger, or serious misconduct | Fails that station only | Policy defines the categories; the scheme names the item |
| Must-pass station | A station the candidate must pass to pass the exam | Fails the exam | Exam-level standard setting, per station |
| Minimum stations passed | A number of stations the candidate must pass in addition to the aggregate | Fails the exam | Exam-level standard setting |

The four are often confused, and the confusion costs marks. A critical item is a property of one item on one sheet. A must-pass station is a property of the station in the exam's pass rule. A critical error on a station that is not must-pass fails the station and leaves the exam decision to the aggregate and the minimum-stations rule. Only when the station is also must-pass does one item fail the whole exam. The [scoring section](/docs/osce/scoring/) covers how the three exam-level conditions combine.

## What qualifies as a critical error?

The policy lists categories, not examples. Three are common:

1. **Patient harm.** An action that would injure the patient if performed in practice: the wrong drug, the wrong site, an unsafe technique.
2. **Failure to act on danger.** Not recognizing or not escalating a finding that demands it: the collapsed patient, the abnormal observation the candidate was given.
3. **Serious professional misconduct.** Behavior toward the patient that would trigger a fitness-to-practice process outside the exam.

Everything else is a mark, not a fail. Forgetting to wash hands is an item. Forgetting to check for allergies before prescribing may be critical. The difference is whether the omission would have harmed the patient in the candidate's presence. The policy states the test in one sentence so that station writers can apply it and reviewers can challenge it.

## How is a critical item written?

The item follows the same rules as any other on the [marking scheme](/docs/osce/design/designing-the-marking-scheme/), with three extra constraints.

- **One action.** "Checked allergies before prescribing" is one action. "Prescribed safely" is a judgment that hides three actions.
- **Observable in the room.** The examiner must be able to see it happen or not happen. If the simulated patient has to report it afterward, it is not a critical item.
- **A stated level.** On a scaled item, the policy says which level fails: usually the lowest, sometimes the lowest two. The scheme prints the rule next to the item, so the examiner sees it while scoring.

The simulated patient script needs a line for it. If the critical item is "asked about anticoagulants", the script must say what the patient answers when asked, and what happens if they are not asked. Without that line, the item is unstable between candidates.

## Who approves, and how is it recorded?

The station writer proposes. The review workshop tests the proposal against the policy's categories. The assessment committee approves the list of critical items for the sitting at the same meeting that approves the blueprint. The record includes the station, item, category, and fail level.

Must-pass stations are approved separately at the exam level when the standard is set. The committee names each one and its reason for doing so. The AMEE guide's examiner training outcomes include procedures for dangerous behavior, meaning the examiner briefing on the day repeats the list and the rule.

## What are candidates told?

Everything except the item wording. The candidate handbook states that some items are critical, what the categories are, that a critical error fails the station, and which stations, if any, are must-pass. Candidates are not told which items are critical on which stations. They are told the rule exists and how it works.

The [regulations page](/docs/osce/planning/regulations-boards-and-appeals/) sets out the grounds for appeal. A critical-error decision is appealed on process: was the policy published, was the item on the approved list, did the examiner apply the stated level. It is not appealed on the clinical judgment the item encodes, because that judgment was made and approved before the exam.

## How many critical items and must-pass stations?

Few. A useful test for the committee: would a graduate who did this on the ward be stopped and spoken to that day? If not, it is a mark. Most stations have none. A station on prescribing or on a procedure may have one. A whole exam rarely needs more than a handful.

Must-pass stations are rarer still. A 2021 paper on conjunctive standards in OSCEs notes that many schools set a minimum number of stations to be passed, and that the practice receives little discussion in the literature and is often set with little justification. The same caution applies to must-pass stations. Each one narrows the compensation the aggregate allows, and each one needs a reason the board can state.

## The policy checklist

- [ ] Define the three categories of critical error in one sentence each.
- [ ] State the test a station writer applies to propose a critical item.
- [ ] Set the rule for scaled items: which level fails.
- [ ] Name the body that approves the list of critical items per sitting, and when.
- [ ] Name the body that approves must-pass stations and the minimum-stations rule.
- [ ] Write the handbook paragraph candidates receive: the rule, the categories, the effect.
- [ ] Add the critical-item rule and the fail level to the marking sheet layout.
- [ ] Add the dangerous-behavior procedure to the examiner briefing.
- [ ] State the appeal grounds for a critical-error decision.
- [ ] Record the approved list with the blueprint sign-off, dated before the exam.

## Limits

The evidence on critical items is thin. The practice is widespread, and regulators' competence tests use it, but there are few studies on how often critical items fire, how examiners apply them, or what they do to reliability. What the literature does say about conjunctive rules is a warning: they change pass decisions, they need a justification, and the justification is usually missing. The policy on this page is the justification, written down.

## Frequently asked questions

### What is a critical error in an OSCE?

An action or omission during a station that would have harmed the patient, missed a danger that demanded action, or amounted to serious professional misconduct. A critical item on the marking scheme detects it. If the candidate scores at or below the stated level on that item, the station is failed regardless of the total.

### What is the difference between a critical item and a must-pass station?

A critical item fails one station. A must-pass station fails the exam. They are set at different levels: the critical item in the marking scheme and the must-pass rule in the exam's standard setting. A critical error on a must-pass station fails the exam; on any other station, it fails the station, and the aggregate rule decides the exam.

### Should candidates be told which items are critical?

Tell them the rule, the categories, and the effect, and which stations are must-pass. Do not tell them which items on which stations are critical. The handbook paragraph is published before the exam and cited at appeal as evidence that the rule was known.

### How many critical items should an OSCE have?

As few as the categories justify. Most stations have none. A prescribing or procedural station may have one. A scheme with several critical items on every station has turned the checklist into a series of fails, and the total stops mean anything. Keep the list short and the reasons written.

### Can a critical-error decision be appealed?

On process, yes. The appeal asks whether the policy was published, whether the item was on the approved list, and whether the examiner applied the stated level. The clinical judgment behind the item was made and approved before the exam and is not reopened for one candidate.

## Sources

**Sources**

1. [Khan KZ, Gaunt K, Ramachandran S, Pushkar P. The Objective Structured Clinical Examination (OSCE): AMEE Guide No. 81. Part II: organisation and administration](https://doi.org/10.3109/0142159X.2013.818635) (Medical Teacher, 2013)
2. [Homer M, Russell J. Conjunctive standards in OSCEs: the why and the how of number of stations passed criteria](https://doi.org/10.1080/0142159X.2020.1856353) (Medical Teacher, 2021)
3. [Homer M. Setting defensible minimum-stations-passed standards in OSCE-type assessments](https://doi.org/10.1080/0142159X.2023.2197138) (Medical Teacher, 2023)

> [!TIP]
> **In practice**
> The policy above becomes two settings: a critical flag with a fail threshold on the item, and a must-pass switch on the station's standard-setting row. To see how StudyDrome applies them and shows the rule to the examiner, read /docs/osce/design/in-studydrome-blueprint-and-stations/.