The psychology case study is a cornerstone assessment across clinical, counselling and applied psychology courses, and it is marked on something more demanding than knowledge: your ability to formulate. Formulation is the skill of weaving a person’s history, thoughts, biology and circumstances into a coherent explanation of why they are experiencing their difficulties — and then using that explanation to justify an intervention. Students lose marks by describing symptoms or listing a diagnosis without explaining how the pieces connect. This guide works through a complete example using an illustrative, fictional client, then gives you the frameworks and method to apply to your own. The same analytical discipline applies to any strong case study, but psychology adds a particular emphasis on formulation and ethics.
Key points
- The heart of the assessment is case formulation, not diagnosis or description.
- Use a recognised model — the biopsychosocial model or the Five Ps (Presenting, Predisposing, Precipitating, Perpetuating, Protective).
- Confidentiality and consent are mandatory — anonymise completely.
- Link the intervention explicitly to the formulation and to evidence (for example, NICE-recommended therapies).
- Evaluate and reflect honestly, including limitations.
What a psychology case study assesses
A psychology case study tests whether you can move from information to understanding to action. Examiners look for accurate, multi-source assessment; a coherent, theory-driven formulation that explains the case rather than just labelling it; an intervention that follows logically from the formulation and rests on current evidence; and genuine ethical awareness — confidentiality, informed consent, and reflexivity about your own role. The single biggest error is confusing diagnosis with formulation. A diagnosis (“generalised anxiety disorder”) names a pattern; a formulation explains how this particular person came to develop and maintain that pattern, which is what tells you how to help them. Markers reward the explanation, not the label. This mirrors the analytical demand in a nursing case study, where reasoning is rewarded over description.
What brings the client now? In their own words where possible.
Relevant developmental, family, medical and social history.
Multi-source: interview, validated measures, observation.
Integrate the information into an explanatory model (biopsychosocial / Five Ps).
An evidence-based plan that follows from the formulation.
Outcomes, limitations and reflexive practice.
Choosing your formulation framework
Two frameworks dominate psychological case studies, and most briefs expect one of them:
| Framework | What it does | Best for |
|---|---|---|
| Biopsychosocial model | Explains the problem across biological, psychological and social domains | Holistic cases; integrating medical and social factors |
| The Five Ps | Structures formulation into Presenting, Predisposing, Precipitating, Perpetuating and Protective factors | Clinical and counselling formulations; the most widely taught |
| CBT formulation (the “hot cross bun”) | Links thoughts, feelings, physical sensations and behaviours | Cognitive-behavioural cases and CBT-based interventions |
| Diagnostic frameworks (DSM-5 / ICD-11) | Classify the presentation | Establishing a diagnosis to sit alongside — not replace — formulation |
The Five Ps is the safest default because it forces you to explain cause, trigger and maintenance — the analytical heart of formulation.
A complete worked example (illustrative, fictional client)
The client below is entirely fictional and used only to demonstrate structure. In your own work, anonymise every real client completely — no names, dates or identifying details — use a pseudonym, and confirm that informed consent and your professional ethical guidelines (for example, the BPS Code of Ethics and Conduct) have been followed. Breaching confidentiality can cap or fail the assignment.
1. Presenting problem
“Ms B”, a fictional 24-year-old postgraduate student, presents with persistent worry, difficulty sleeping, poor concentration and physical tension over the past six months, worsening as her thesis deadline approaches. She describes feeling “constantly on edge” and avoiding her supervisor. Recording the presenting problem in the client’s own framing — not immediately translated into jargon — respects her perspective and gives the reader the raw material the formulation will go on to explain.
2. Background and assessment
Relevant history (kept selective and relevant) includes a high-achieving, critical family environment, a previous brief episode of anxiety during undergraduate exams, and limited current social support having recently relocated. Assessment should be multi-source: a clinical interview, a validated self-report measure such as the GAD-7 (which might indicate moderate-to-severe anxiety), and behavioural observation. Using more than one source — and interpreting the scores rather than just reporting them — demonstrates rigorous, triangulated assessment.
Choosing validated measures is part of the skill. A good case study names appropriate, psychometrically sound instruments and says briefly why they fit — for an anxiety presentation, the GAD-7 for symptom severity, perhaps the PHQ-9 to screen for co-occurring low mood, and a functioning measure to capture impact on daily life. Crucially, scores are interpreted in context rather than treated as verdicts: a moderate-to-severe GAD-7 alongside Ms B’s avoidance and sleep disruption builds a converging picture, and it is that convergence — not any single number — that gives the assessment its weight. Note, too, any limitations of the measures, such as their reliance on self-report and the influence of the testing context.
3. Formulation (Five Ps)
This is the core of the assessment. The Five Ps integrate the information into an explanation:
| Factor | Applied to Ms B |
|---|---|
| Presenting | Persistent worry, insomnia, poor concentration, physical tension; avoidance of supervisor |
| Predisposing | High-achieving, critical family environment; prior anxiety episode — vulnerability to perfectionism and self-criticism |
| Precipitating | Thesis deadline and recent relocation removing usual support |
| Perpetuating | Avoidance of the supervisor and of the work, which reduces anxiety briefly but prevents progress and reinforces worry |
| Protective | Insight into the problem, prior recovery, motivation to seek help |
Notice the explanatory power: the perpetuating factor (avoidance) shows precisely why the anxiety is self-sustaining — and therefore precisely where the intervention should aim. That causal chain is what separates a formulation from a description.
4. Intervention
The intervention must follow from the formulation and the evidence base. Given an anxiety presentation maintained by avoidance and unhelpful cognition, a cognitive-behavioural approach is well supported by the evidence (and recommended in guidelines such as NICE for generalised anxiety). A plan might include psychoeducation about the anxiety cycle, cognitive restructuring of perfectionistic beliefs, graded exposure to the avoided supervisor meetings and thesis work, and relaxation or sleep-hygiene strategies. Each element should be tied back explicitly to a perpetuating or predisposing factor in the formulation — that link is what earns the marks.
5. Evaluation and reflection
Evaluation considers how outcomes would be measured (for example, repeating the GAD-7 over time and tracking behavioural goals such as supervisor contact) and discusses limitations honestly — the constraints of a single-case account, the role of factors outside therapy, and your own assumptions. Reflexivity — awareness of how your perspective shapes the formulation — is a hallmark of strong psychological writing and is increasingly assessed in its own right.
“A diagnosis names the pattern. A formulation explains how this person came to live inside it — and only the explanation tells you how to help.”
Beyond the clinical case study: single-case designs
Not every psychology case study is a clinical formulation. Some briefs — particularly in research-methods or behavioural modules — ask for a single-case experimental design, which studies one participant systematically to test whether an intervention causes change. The most common is the AB design, which compares a baseline phase (A) with an intervention phase (B); the more rigorous ABA and ABAB (reversal) designs withdraw and reinstate the intervention to demonstrate that it, rather than something else, is responsible for the change. A multiple-baseline design introduces the intervention at different times across behaviours or settings to strengthen causal inference without withdrawal. If your brief is of this type, the emphasis shifts from formulation to measurement: defining the target behaviour operationally, charting data across phases, and interpreting the visual and statistical change. Recognising which kind of case study you have been set — clinical formulation or single-case experiment — is the first decision to get right, because the two are marked on different criteria.
| Design | Structure | What it demonstrates |
|---|---|---|
| AB | Baseline (A) then intervention (B) | Change coincides with the intervention — a weak causal claim |
| ABA / ABAB | Withdraw and reinstate the intervention | Stronger causal inference: behaviour tracks the intervention’s presence |
| Multiple-baseline | Stagger the intervention across behaviours, settings or people | Causal inference without withdrawing a helpful intervention |
Whichever design you use, define the target behaviour operationally so it can be measured reliably, collect enough baseline data to establish a stable pattern before intervening, and present results visually on a phase chart. Interpretation focuses on the level, trend and variability of the data across phases, not on inferential statistics alone, which single cases rarely support.
Integrating theory and evidence
Strong psychological case studies are saturated with evidence, but integrated rather than bolted on. Draw on current, peer-reviewed sources and recognised clinical guidelines, and place each citation at the exact point where it justifies a decision — the choice of assessment measure, the theoretical model behind the formulation, the selection of intervention. Where the evidence is mixed, say so: acknowledging that a recommended therapy has limitations for a particular presentation demonstrates the critical appraisal that higher grades require. Be wary of over-claiming from a single case; the value of a case study lies in the depth and coherence of its reasoning, not in generalisable proof. Apply Harvard or APA referencing consistently — psychology overwhelmingly uses APA — and make sure every in-text citation appears in the reference list and vice versa, because inconsistent referencing is among the easiest ways to lose marks on otherwise strong work.
Ethics and confidentiality in psychological case studies
Ethics is not a box to tick at the end of a psychology case study; it runs through the whole piece. Anonymise the client completely and use a pseudonym. Where the case is based on a real person, confirm and state that informed consent was obtained and that you have worked within your professional code (in the UK, the British Psychological Society’s Code of Ethics and Conduct). Be careful, too, with the power of language: formulation should be respectful and non-pathologising, framing difficulties as understandable responses to circumstances rather than as deficits in the person. Demonstrating this ethical sensibility — and reflecting on dilemmas where they arise — signals the professional maturity that distinguishes higher-graded work.
How to structure the written case study
- Introduction — the context, the brief and an ethics/confidentiality statement.
- Presenting problem — in the client’s own framing.
- Background and assessment — relevant history; multi-source assessment interpreted.
- Formulation — an explanatory model (Five Ps / biopsychosocial).
- Intervention — evidence-based and linked to the formulation.
- Evaluation and reflection — outcomes, limitations, reflexivity.
- Conclusion and references — concise close; rigorous Harvard or APA.
Undergraduate vs postgraduate expectations
At undergraduate level, examiners want a clear, accurate formulation using a recognised framework and an evidence-linked intervention. At postgraduate and clinical-training level, expectations rise sharply: integration of multiple theoretical models, critical appraisal of the evidence base, sophisticated reflexivity, and nuanced handling of ethical complexity. Postgraduate markers penalise purely descriptive accounts and reward genuine clinical reasoning. Whatever your level, re-read your learning outcomes and your module requirements, and calibrate the depth of formulation accordingly.
Common mistakes that cost marks
- Confusing diagnosis with formulation — labelling instead of explaining.
- Describing symptoms without integrating them into a causal model.
- Breaching confidentiality — any identifying detail can cap or fail the work.
- An intervention disconnected from the formulation — generic “do CBT” with no link to the maintaining factors.
- Single-source assessment — relying on the interview alone.
- No reflexivity — ignoring your own role and the limits of the account.
- Weak referencing — inconsistent or missing Harvard/APA citations.
Reflexivity and the limits of a single case
Mature psychological writing is reflexive: it acknowledges that the psychologist is not a neutral observer but an active participant whose assumptions, training and relationship with the client shape the formulation. A high-scoring case study makes this explicit — noting, for instance, how your own theoretical preferences might have led you to emphasise cognitive factors over systemic ones, or how the therapeutic relationship may have influenced what the client disclosed. It also handles the limitations of the case-study method honestly: a single case cannot establish that an intervention works in general, only that it appeared to help this person in this context. Far from weakening your work, candidly addressing these limits demonstrates exactly the critical, self-aware practice that professional bodies expect — and that distinguishes a thoughtful clinician-in-training from a student simply applying a template.
Finally, remember that formulation is a working hypothesis, not a fixed verdict. The best case studies present the formulation as something to be tested and revised as new information emerges, rather than as a settled truth — mirroring how formulation is actually used in clinical practice.
Related guides
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