What is the cover-the-options rule in MCQ writing?
The cover-the-options rule is a quality check from Case and Swanson's NBME item-writing guide: cover the answer choices and read only the stem. If a knowledgeable examinee can supply the answer from the stem alone, the item is focused; if not, the stem needs rewriting.
The cover-the-options rule (sometimes called the "cover-the-options test") is the simplest and most useful quality check in multiple-choice writing. It comes from Case and Swanson's NBME guide, Constructing Written Test Questions for the Basic and Clinical Sciences, and it takes about ten seconds per item:
- Cover the answer options with your hand.
- Read the stem.
- Ask: could an examinee who knows this material answer the question without seeing the options?
If yes, the stem is focused — it poses a complete, answerable question, and the options merely let the examinee recognize the answer they already generated. If no, the stem is doing too little work, and the item almost certainly has a structural flaw.
What failing the test looks like
Stems that fail the cover-the-options test usually take one of these forms:
- Unfocused stems. "Which of the following statements about warfarin is true?" poses no question at all; the examinee must read four unrelated statements and fact-check each one. These items are really four true/false questions in a trench coat, and they cannot be answered from the stem.
- Incomplete lead-ins. A stem that trails off ("Warfarin…") forces the options to complete a sentence, which invites grammatical cues and heterogeneous options.
- Vignettes with no question. A rich clinical scenario followed by "Which of the following is true?" wastes the vignette — the examinee still can't form an answer until the options reveal what's being asked.
Why it matters
A focused stem tests whether the examinee can generate the answer — retrieve a diagnosis, choose a next step, predict a mechanism — which is closer to the cognition medical education is trying to assess. An unfocused stem tests whether the examinee can verify statements, a lower-order task that also takes longer to read and is more vulnerable to option-based flaws. Haladyna, Downing and Rodriguez (2002) include "the stem should contain the central idea" among their evidence-based guidelines, and unfocused stems are one of the most common item-writing flaws found when faculty-written exams are audited.
How to use it in practice
Apply the test twice: once as the writer, immediately after drafting, and once during peer review. The fix for a failing item is almost always the same — rewrite the stem as a direct question ("What is the most likely diagnosis?", "Which drug is the best next step?") and rebuild the options as a homogeneous set of short, parallel answers to that question. Items that pass the cover-the-options test also tend to survive statistical review after administration, because focused stems produce cleaner discrimination.
For the full item-drafting workflow this check belongs to, see how to write flaw-free MCQs.