How to Write Research Objectives

Research objectives state what the study will do to answer the research question. Good objectives are specific, measurable and directly linked to the outcomes, methods and analysis; there is usually one primary objective and a small number of secondary ones.

Structure

• General aim: the overall purpose in one sentence.
• Primary objective: the main thing you will estimate or test; it drives the sample size.
• Secondary objectives: additional questions; keep few.
• Exploratory objectives (if any): labelled as such.

Writing them

1. Start with an action verb: determine, estimate, compare, describe, evaluate, identify.
2. Name the population and the measure.
3. Avoid vague verbs such as understand or explore unless the study is genuinely exploratory.
4. Check that each objective has a matching outcome and analysis.

Illustrative example

Invented for teaching. Aim: to evaluate the association between preoperative anaemia and postoperative delirium. Primary objective: to estimate the proportion of patients aged over 65 undergoing hip fracture surgery who develop delirium within 7 days. Secondary objectives: to compare delirium proportions between anaemic and non-anaemic patients; to describe length of stay by delirium status.

Linking objectives to the rest of the protocol

Each objective should have a matching primary or secondary outcome, a data source and a planned analysis. A simple table with the columns objective, outcome, how measured, analysis shows gaps quickly. If an objective has no outcome, remove it; if an outcome has no objective, either add the objective or drop the outcome. The primary objective is the one on which the sample size calculation is usually based, so it should be the most important and the most measurable.

Common pitfalls

• Too many objectives for one study.
• Objectives that cannot be measured with the data you have.
• Changing objectives after seeing the results without saying so.

Key takeaways

• One primary objective, a few secondary ones.
• Verb + population + measure.
• Every objective should map to an outcome and analysis.

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.