Week 7

Question 1

What is a systematic review (SR)?

Answer 1

A structured, transparent review that answers a focused research question by systematically searching, selecting, appraising, and synthesising all relevant primary studies.

Question 2

Why are SRs near the top of the evidence pyramid?

Answer 2

They reduce bias via pre-defined protocols (e.g., PRISMA-P), combine multiple studies, and provide an objective summary for practice and policy.

Question 3

List three key strengths of SRs.

Answer 3

(i) Reduced bias, (ii) increased statistical power when pooled, (iii) time-efficient synthesis for clinicians.

Question 4

List three main weaknesses of SRs.

Answer 4

(i) Publication bias, (ii) heterogeneity between studies, (iii) “garbage in–garbage out” if included studies are poor.

Question 5

Name two checklist items you look for when critically evaluating an SR.

Answer 5

Clear question & eligibility criteria, comprehensive search strategy, risk-of-bias assessment, transparent synthesis.

Question 6

What distinguishes a meta-analysis (MA) from a systematic review?

Answer 6

MA is the statistical pooling of effect sizes from studies (usually within an SR) to generate a precise summary estimate.

Question 7

Give two strengths of MAs.

Answer 7

(i) Greater statistical power & narrower CIs, (ii) resolves conflicting results by providing a weighted average.

Question 8

Give two weaknesses of MAs.

Answer 8

(i) Susceptible to publication bias, (ii) heterogeneity (“apples vs oranges”) can mislead if studies are too diverse.

Question 9

What statistical tool quantifies heterogeneity in a MA?

Answer 9

I² statistic (0–100 %); higher values indicate greater between-study variability.

Question 10

What are observational studies?

Answer 10

Non-interventional designs that observe exposures/outcomes in real-world settings to explore associations.

Question 11

Name the three main types of observational study.

Answer 11

Cohort, case-control, and cross-sectional.

Question 12

Contrast prospective vs retrospective designs.

Answer 12

Prospective: follow subjects forward from exposure to outcome; Retrospective: look backward after outcome occurred.

Question 13

Two key strengths of observational studies.

Answer 13

Ethical for harmful exposures; high external validity (real-world).

Question 14

Two major weaknesses of observational studies.

Answer 14

Vulnerable to confounding & bias; unable to prove causation.

Question 15

What protocol items minimise bias in observational studies?

Answer 15

Rigorous participant selection, clear exposure/outcome definitions, statistical adjustment for confounders.

Question 16

Primary purpose of an RCT.

Answer 16

To test efficacy/safety of an intervention while minimising bias through randomisation and blinding.

Question 17

Three blinding levels in RCTs.

Answer 17

Single-blind (participants), double-blind (participants + researchers), triple-blind (participants + researchers + analysts).

Question 18

One strength and one weakness of RCTs.

Answer 18

Strength: strongest causal evidence; Weakness: costly and may lack real-world generalisability.

Question 19

Strengths & weaknesses of a systematic review

Answer 19

Strengths: reduces bias, increases power, broad generalisability, clear clinical guidance.
Weaknesses: publication bias, heterogeneity, depends on primary study quality, time-consuming

Question 20

Critical appraisal of an SR – key considerations

Answer 20

Focused question (PICO/PCC)

Comprehensive multi-database search (+ grey literature)

Explicit inclusion/exclusion criteria

Risk-of-bias assessment (e.g., ROBIS)

Transparent synthesis & limitations reporting

Question 21

Strengths & weaknesses of a meta-analysis

Answer 21

Strengths: higher precision, detects small effects, resolves study disagreement, hypothesis generation.
Weaknesses: sensitive to publication bias; heterogeneity; quality of pooled studies; requires advanced stats.

Question 22

Critical appraisal of a meta-analysis

Answer 22

Same items as SR plus:
* Assessment of publication bias (funnel plot, Egger test)
* Exploration of heterogeneity (I², subgroup/meta-regression)
* Appropriate model choice (fixed vs random effects)
* Sensitivity analyses reported

Question 23

Differences between scoping and narrative reviews

Answer 23

Scoping review: maps breadth of literature, identifies gaps, uses systematic search but usually no critical appraisal.

Narrative review: broad, author-driven overview; flexible search, may lack explicit methods.

Question 24

6. Review components to check

Answer 24

Review question clarity

Sources searched (databases, grey lit)

Selection criteria pre-specified & transparent

Data evaluation tools (risk-of-bias, quality scores)

Implications for practice explicitly stated

Question 25

7. Use of an RCT

Answer 25

To establish cause–effect relationships for an intervention under controlled conditions.

Question 26

RCT strengths & weaknesses

Answer 26

Strengths: randomisation minimises confounding; blinding reduces bias; gold-standard for efficacy. Weaknesses: costly, ethical limits, strict criteria reduce generalisability, adherence issues.

Question 27

9. Three types of blinding in an RCT

Answer 27

Single, double, triple (definitions in Flashcard 17).

Question 28

11. Critical appraisal points for observational studies

Answer 28

Clear exposure/outcome definitions Temporal relationship demonstrated (esp. prospective) Control of confounders (stratification, multivariable models) Bias assessment (selection, recall, observer) Adequate follow-up (cohort)

Question 29

12. Three types of observational study

Answer 29

Cohort: follow exposed & unexposed groups forward. Case-control: start with outcome, look back for exposure. Cross-sectional: assess exposure & outcome at a single time-point.

Question 30

13. Critically appraise provided articles

Answer 30

Use above appraisal checklists—evaluate design appropriateness, bias control, sample size, exposure/outcome validity, statistical adjustment, and consistency of conclusions with data.