What is the single most common mistake?

Answering the scenario rather than the question. The scenario sets up a situation; the question that follows asks something specific about it. Applicants who read the scenario, get absorbed in it, and then write a general response to the situation lose marks on questions they could have answered easily.

Is it a mistake to say I would ask for more information?

Only if that is all you say. Saying you would find out more and then stopping is an answer that never decides anything. Say what you would ask, then say what you would do depending on what you heard. The branch is the part that scores.

Does one weak scenario ruin my test?

No. Acuity states that each scenario is scored by a different rater rather than one rater scoring the whole test, so the rater who read your worst answer never sees your best one. The realistic risk is not the scenario, it is the ten minutes of rattled writing that follows it.

Is it a mistake to write short answers?

Short is not the problem. Incomplete is. A tight answer that validates, finds out, weighs and decides beats a long one that circles. Length is a symptom, not a cause.

Should I use clinical or ethical terminology?

Only if it is doing work. Naming a principle and then not applying it is the most visible form of padding there is. Describing what you would actually do is what a rater can score.

Common CASPer Mistakes

The most common CASPer mistakes are answering the situation instead of the question asked, deciding from facts you were never given, writing values instead of actions, running out of clock with the structure half built, and letting one bad scenario damage the rest of the test.

The most common CASPer mistakes are these five, in the order they cost applicants marks: answering the situation instead of the specific question asked; deciding what happened from facts the scenario never gave you; writing about values rather than actions; running out of time with the structure half built; and letting one bad scenario wreck the ten minutes after it. None of them is a knowledge problem. All five are process problems, which is why reading more sample answers does not fix them and timed rehearsal with marking does.

Mistake one: answering the scenario, not the question

The scenario is the setup. The question underneath it asks something specific, and it is often narrower than the situation. Applicants get absorbed in the situation, write a general response to it, and never address what was asked.

The fix is mechanical and takes four seconds: read the question, then read it again before you type. If the question asks what you would say to a particular person, the answer is words you would say to that person. If it asks how you would decide, the answer is a decision process. Matching the form of your answer to the form of the question is close to free marks and a startling number of applicants leave it on the table.

Mistake two: deciding from facts you were never given

Almost every scenario is under-specified on purpose. Two readings are available and the test wants to see whether you notice. The weak move is to pick the uncharitable reading immediately and then act decisively on it, which feels like strength and reads as carelessness.

Check before you assume. Say out loud which part is ambiguous, say what you would ask to resolve it, and then say what you would do under each answer. That is not fence-sitting, it is the opposite: it is committing to an action twice instead of once.

Mistake three: values instead of actions

“Patient safety is paramount.” “Honesty is the foundation of the profession.” “I value open communication.” These sentences are all true and none of them is an answer. A rater cannot score a value; they can score what you would do.

Swap every abstract noun for a verb and a person. Not “I would ensure transparency”, but “I would tell him I was going to raise it, before I raised it.” Not “I would prioritise patient safety”, but “I would stop the pack leaving the counter and check the label against the file myself.”

Mistake four: running out of clock

The typed section is timed and a structure you cannot finish scores like a structure you do not have. Two causes, with two different fixes.

If you type slowly, practise typing, not scenarios. Below roughly 40 words a minute, the clock is the binding constraint and no amount of reasoning practice loosens it.

If you type fine but still run out, you are spending too long on the opening. Long preambles restating the scenario are the single biggest time sink I see when marking. The rater has read the scenario. Start at your first substantive sentence.

Mistake five: carrying a bad scenario forward

This is the expensive one. Acuity states that each scenario is scored by a different rater, so the rater who read your weakest answer never sees the rest of your test. The damage from a bad scenario is bounded. The damage from spending the next two scenarios thinking about it is not.

Build a reset. Mine is one breath and one sentence: that one is gone, this one is new. It sounds trivial. It is worth more marks than any content tip on this page.

A scenario, and two answers

You are shadowing on a hospital ward. In the corridor, a patient’s adult daughter stops you, sees your student badge, and asks whether her mother’s biopsy result has come back and what it showed. You do not know, and you are not part of the care team.

A weak answer. “I would explain that I am a student and cannot discuss patient information due to confidentiality, and direct her to the nursing staff. Patient privacy is a fundamental professional obligation and it would be inappropriate for me to comment on a case I am not involved in.”

A strong answer. “I would say I do not know, first, because that happens to be true and it is the part she will want most. Then I would say the rest plainly: I am a student here to learn, I am not on her mother’s team, and results are not mine to give even if I had them. I would not leave it there, because ‘not my place’ is the answer that sends people back to a corridor to wait. I would ask who she has spoken to so far, since she may already have been told someone would come and nobody has, and that is a fixable problem. Then I would go and find the nurse or resident myself and tell them she is waiting and what she is asking, rather than pointing down the hall. If there is a family room I would show her where it is. What I would not do is speculate about timelines, say results usually take a few days, or offer reassurance about what the result might be, because all three sound helpful and all three are me inventing information about a case I know nothing about.”

What separates them. The weak answer is correct and cold. It hides behind a rule, does the minimum, and hands a frightened person a direction instead of a person. It also opens with its own status rather than her question. The strong answer answers the question first, explains the limit in ordinary language rather than as policy, finds out what has already happened, takes one concrete action on her behalf instead of delegating with a gesture, and then names three specific tempting things it would not do. That last move, saying what you would avoid and why, is one of the cheapest ways to show judgment, and almost nobody does it.

Key numbers

Five common mistakes: wrong question, invented facts, values instead of actions, clock, and carrying a bad scenario forward.
One different human rater per scenario, so a bad scenario is contained.
Two sections, video response and typed response, and most applicants rehearse only one.
Below about 40 words a minute, typing speed is your binding constraint.
Acuity recommends the official practice test at the same time of day and in the same location as the real sitting.

If you want these marked out of your own writing rather than recognised on a page, that is what the CASPer programs do.

Last reviewed 17 September 2026. Written by Arvin Ardakani, final-year medical student, 4th quartile on CASPer four times.

What are the most common CASPer mistakes?

Key facts

Mistake one: answering the scenario, not the question

Mistake two: deciding from facts you were never given

Mistake three: values instead of actions

Mistake four: running out of clock

Mistake five: carrying a bad scenario forward

A scenario, and two answers

Key numbers

Sources

Frequently asked

Want this taught, not just read?