Forest Plot
The forest plot displays effect estimates and their 95% CIs for multiple studies or subgroups, with a pooled summary estimate at the bottom. It is the standard display for meta-analyses and subgroup analyses. The pooled estimate diamond, the heterogeneity statistics (Iツイ, Q test p-value), and the model choice (fixed vs. random effects) are all mandatory disclosures.
STEP 1 —When to Use
Use a forest plot when: you are presenting a meta-analysis of multiple studies; you are showing subgroup analyses within a single study (e.g., effect by age group, sex, disease stage); you want to visually display how individual study estimates relate to the pooled estimate; you are comparing effect estimates across multiple predictors in a regression model (coefficients with CIs).
Fixed vs. random effects: use random effects when heterogeneity is present (Iツイ > 25%) or when studies are not exchangeable (different populations, designs). Use fixed effects only when studies are genuinely homogeneous and exchangeable. The choice must be pre-specified and justified.
STEP 2 —Journal Requirement
- Effect metric must be labeled: RR, OR, HR, SMD, MD, etc.
- Model type (fixed / random effects) and the basis for model selection must be stated.
- Heterogeneity statistics: Iツイ with 95% CI, Cochran's Q with p-value —both required.
- Study weights (as percentages) should be shown (either as numbers or as proportional square sizes).
- Reference line at 1.0 (for ratio measures) or 0.0 (for difference measures) must be present.
- PRISMA guidelines (for systematic reviews) require the search strategy and inclusion criteria to be referenced.
STEP 3 —Licklider Implementation
Input
- Study/subgroup labels, effect estimates, and 95% CIs (or SEs)
- Effect metric type: RR, OR, HR, MD, SMD
- Model: random effects (DerSimonian-Laird, default), fixed effects, or user-specified
- Optional: subgroup headers for grouped forest plots
Output
- Horizontal CI lines with squares proportional to study weight
- Pooled estimate diamond (width = 95% CI, height = effect size scale)
- Reference vertical line at null effect
- Right-side numeric table: estimate and CI for each study
- Weight column (percentage) for each study
- Heterogeneity statistics annotated below the diamond: Iツイ, Q, p
- Model type labeled
STEP 4 —Draft Output (Draft / Needs review)
Forest plot of [effect measure] for [outcome] across [N] studies.
Effect sizes and 95% confidence intervals are shown for each study.
Square size is proportional to study weight. The summary estimate was
calculated using a random-effects model (DerSimonian-Laird method),
chosen due to expected between-study heterogeneity in populations
and interventions. Pooled [RR/OR/HR/MD] = 1.42 (95% CI [1.18, 1.71]).
Heterogeneity: Iツイ = 34% (95% CI [0%, 68%]), Q(4) = 6.1, p = 0.19.
The vertical reference line is drawn at the null value ([1.0 / 0.0]).