Psych Vivas · Foundations — research methods and study design
Research methods and study design — structured clinical viva
Fellowship viva on design selection, observational versus experimental threats, reporting standards, and evidence synthesis.
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Target exams
Interpretation
Reveal interpretation
Drug X vs Y programme. As proposed, this is a non-randomised comparative study, not an RCT. Confounding by indication (sicker patients channelled to one drug), open-label performance/detection bias on PANSS, and completer analysis (attrition) are fatal threats for a causal therapy claim.[1][4][7] Redesign: parallel-group RCT with random sequence, allocation concealment, blinding of outcome assessors at minimum, pre-specified primary outcome, and ITT primary analysis, reported with CONSORT.[2][7][8] If randomisation is truly impossible, label it observational, use ROBINS-I thinking, and avoid causal marketing language.
Catchment depression and unemployment. Single-time household survey is a cross-sectional design: appropriate for prevalence if sampling and response are rigorous; association with unemployment cannot establish direction (unemployment → depression vs depression → job loss).[1][4] Report with STROBE cross-sectional items; do not claim incidence or strong causation without longitudinal data.[3]
Meta-analysis after systematic search. A systematic review can stop at structured narrative synthesis; meta-analysis is optional when studies are sufficiently similar clinically and statistically. PRISMA governs reporting of the review process, not a mandate to pool incompatible trials.[5]
Follow-ups. Concealment ≠ blinding.[8][2] Hill criteria help weigh observational associations (temporality, strength, consistency, etc.) without replacing experimental evidence when RCTs are feasible.[6]
Key points
[1] [2] [5]References
- [1]Grimes DA, Schulz KF An overview of clinical research: the lay of the land Lancet, 2002.PMID 11809203
- [2]Schulz KF, Altman DG, Moher D; CONSORT Group CONSORT 2010 statement: updated guidelines for reporting parallel group randomised trials BMJ, 2010.PMID 20332509
- [3]von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP; STROBE Initiative The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies Lancet, 2007.PMID 18064739
- [4]Grimes DA, Schulz KF Bias and causal associations in observational research Lancet, 2002.PMID 11812579
- [5]Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews BMJ, 2021.PMID 33782057
- [6]Hill AB The environment and disease: association or causation? Proc R Soc Med, 1965.PMID 14283879
- [7]Hollis S, Campbell F What is meant by intention to treat analysis? Survey of published randomised controlled trials BMJ, 1999.PMID 10480822
- [8]Schulz KF, Chalmers I, Hayes RJ, Altman DG Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials JAMA, 1995.PMID 7823387