The aim and objectives are the shortest part of your synopsis, but reviewers read them first. They decide whether your methods, sample size and statistics make sense. Weak objectives are one of the most common reasons an ethics committee or university sends a synopsis back.
Aim vs objectives
- Aim: one sentence describing the overall purpose of the study. It can be broad.
- Objectives: the specific, measurable steps that together achieve the aim. Each objective should be something you can answer with data at the end of the study.
A simple test: every objective should map to at least one table in your results chapter. If you cannot imagine the table, rewrite the objective.
Primary and secondary objectives
- Primary objective: the main question. Your sample size is calculated for this one. Keep it to one, or at most two.
- Secondary objectives: additional questions your data can answer, such as associations, subgroups or complications. Two to four is usually enough.
Use action verbs that can be measured
Good verbs: to estimate, to determine, to compare, to assess, to correlate, to evaluate.
Verbs to avoid on their own: "to study", "to know", "to understand", "to see". They do not say what you will measure.
Match the verb to your design:
- Cross-sectional: to estimate the prevalence…, to describe the clinical profile…
- Correlation: to correlate X with Y…
- Comparative: to compare the efficacy of A and B in terms of…
- Prognostic or cohort: to assess the association of X with outcome Y…
- Diagnostic: to determine the sensitivity and specificity of X against Y…
Worked example 1: observational study
Title: Clinical profile and outcome of acute kidney injury in elderly patients at a tertiary care hospital
Aim: To study the clinical profile and in-hospital outcome of acute kidney injury in patients aged 60 years and above.
Primary objective: To determine the in-hospital mortality of acute kidney injury in elderly patients.
Secondary objectives:
- To describe the aetiology and KDIGO stage of acute kidney injury in these patients.
- To assess the association of KDIGO stage with mortality and need for dialysis.
- To estimate the proportion of patients with renal recovery at discharge.
Worked example 2: comparative study
Title: Comparison of ultrasound-guided and landmark-guided internal jugular vein cannulation in adult ICU patients
Aim: To compare ultrasound-guided and landmark-guided techniques for internal jugular vein cannulation.
Primary objective: To compare the first-attempt success rate of the two techniques.
Secondary objectives:
- To compare the number of attempts and access time.
- To compare the incidence of complications such as arterial puncture and haematoma.
Should you write a hypothesis?
For comparative and analytical studies, yes. State a null hypothesis (no difference between groups) and an alternative hypothesis. For purely descriptive studies a hypothesis is optional; many universities accept "not applicable".
Checklist before you submit
- One clear aim.
- One primary objective, and the sample size is calculated for it.
- Every objective starts with a measurable verb.
- Every objective names what is measured and in whom.
- The objectives match the title, without adding new conditions or outcomes.
See it done for your title
Every speciality page on this site shows one free sample of objectives written in this format. For any other title you can unlock the aim, objectives and hypothesis on screen in about a minute with Get Objectives, or see a complete sample synopsis first. Browse titles on the all specialities page.