How to Avoid Choosing an Overly Broad Research Topic

A topic is too broad if you cannot state one specific question, one population and one primary outcome in a sentence, or if you would need dozens of studies to answer it. Narrow it by limiting who, what, where and when, until a single study could answer it.

Signs of a too-broad topic

• The title is a whole disease or specialty ("diabetes", "cardiology").
• Many possible outcomes, none designated primary.
• Search results number in the tens of thousands.
• You cannot decide what data to collect.

Ways to narrow

Illustrative example

Invented for teaching. Start: "Diabetes and kidney disease". Narrow step by step: type 2 diabetes in adults; in outpatient clinics in one city; use of SGLT2 inhibitors; outcome: estimated GFR decline over 2 years. Final: "Among adults with type 2 diabetes attending city outpatient clinics, is SGLT2 inhibitor use associated with slower eGFR decline over 2 years?"

Testing whether your topic is narrow enough

Try to write the title of your future paper. If the title needs more than one "and", the topic is probably too broad. Then try to write the first sentence of your Methods: "We included adults who...". If you cannot finish the sentence in one line, the population is not yet defined. Finally, count how many outcomes you plan to analyse; more than three often signals a topic that needs another narrowing step or a clearer primary outcome.

Common pitfalls

• Narrowing until the sample is too small to analyse.
• Narrowing the population but leaving five outcomes.

Key takeaways

• One population, one exposure, one primary outcome.
• If narrowing leaves too few cases, widen the time or setting, not the outcomes.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.