Research Methods

Meta-Analysis & Evidence Synthesis

A single study rarely settles a question. We pool the evidence properly—a pre-registered protocol, a reproducible search, careful effect-size extraction, and the right synthesis model—so your review says what the whole literature supports, not just what one dataset happened to show.

Systematic reviews & meta-analysis PRISMA-standard reporting R (metafor) · Stata Reproducible, journal-ready
Sample meta-analysis forest plot A forest plot showing seven study effect sizes as squares with horizontal confidence-interval lines, arranged around a vertical null line, with a pooled random-effects estimate shown as a diamond at the bottom. meta_analysis · random effects 0 −0.5 +0.5 Standardized effect size (95% CI) Study 1Study 2Study 3 Study 4Study 5Study 6Study 7 Pooled
Sample output study effect pooled estimate
Overview

Synthesis that says what the evidence supports

A meta-analysis is only as trustworthy as the process behind the number. A pooled effect built on a search that missed half the literature, effect sizes extracted inconsistently, or a fixed-effects model masking real heterogeneity will produce a confident-looking estimate that a referee can dismantle. The credibility lives in the protocol, not the forest plot.

We treat the review as a designed study. That means a pre-specified protocol and inclusion criteria, a documented and reproducible search across the right databases, transparent screening with inter-rater checks, and careful, consistent effect-size extraction—before any pooling happens. Then the synthesis model is chosen to match the evidence: random-effects where heterogeneity is real, multilevel or three-level structures for dependent effects, meta-regression to explain variation rather than average it away.

What you receive is a defensible summary of a whole literature: the pooled estimate, its heterogeneity and its sources, a full publication-bias assessment, and a PRISMA-compliant write-up reproducible from the search string forward.

Who We Work With

For anyone synthesizing a body of evidence

If your question is "what does the literature as a whole say," this is the right desk to write to.

PhD Researchers & Doctoral Candidates

A systematic review or meta-analysis chapter done to standard—a strong, citable contribution that also frames the rest of your thesis.

Faculty & Academic Researchers

Review and synthesis capacity for a high-visibility paper, with the screening and modeling handled to current methodological standards.

Research Institutes & Think Tanks

Evidence synthesis that consolidates a field—the kind of review that becomes a reference point for later work.

Policy Organizations

Evidence reviews for decisions, where knowing the weight and consistency of the evidence matters as much as any single study.

Journals & Editorial Teams

Independent methodological review of submitted systematic reviews and meta-analyses where synthesis rigor is in question.

Research Groups With Longitudinal Evidence

Teams synthesizing cross-lagged or panel findings across studies—where continuous-time methods (CoTiMA) apply.

Capabilities

The full synthesis toolkit, matched to your evidence

Organized from review design through advanced synthesis. If your evidence base needs a method not listed here, ask—this is the core, not the boundary.

Review Types

Structured evidence reviews

The right review format for your question and evidence base—each with its own protocol and reporting standard.

  • Narrative reviews
  • Systematic reviews
  • Scoping reviews
  • Integrative reviews
  • Umbrella reviews
  • Systematic model reviews
Meta-Analytical Methods

Pooling, explaining & stress-testing effects

From conventional pooling to models for dependent effects, network comparisons, and rigorous bias assessment.

  • Conventional meta-analysis
  • Meta-regression
  • Multilevel meta-analysis
  • Three-level meta-analysis
  • Bayesian meta-analysis
  • Network meta-analysis
  • Multivariate meta-analysis
  • Dose-response meta-analysis
  • Cumulative meta-analysis
  • Robust variance estimation
  • Publication-bias analysis
  • Sensitivity analysis
  • Meta-analytic SEM
Advanced Longitudinal Synthesis

Time-aware evidence synthesis

For pooling longitudinal and cross-lagged effects measured across studies with different time lags.

  • Longitudinal meta-analysis
  • Cross-lagged meta-analysis
  • CoTiMA (continuous-time)
  • Continuous-time meta-analytic models
How the Analysis Works

Six steps from question to pooled evidence

A transparent, PRISMA-aligned sequence—the protocol fixed before screening and every decision documented in the final review. Nothing is a black box.

Steps are adapted to your evidence base: the number and comparability of studies, the effect-size metric, and whether the effects are dependent or measured over time. We confirm the protocol with you before screening begins.

  1. 1

    Protocol

    Define the question, inclusion criteria, effect-size metric, and analysis plan—pre-registered before any study is seen.

    Inputs: question · PICO/criteria · effect metric

  2. 2

    Search

    Build and run a reproducible search across the right databases, then deduplicate—documented so it can be re-run exactly.

    Sources: Scopus · Web of Science · databases · grey literature

  3. 3

    Screen & extract

    Title/abstract and full-text screening with inter-rater checks, then consistent effect-size and moderator extraction.

    Steps: screening · inter-rater · extraction · risk of bias

  4. 4

    Synthesize

    Pool effects with the model the evidence requires, quantifying heterogeneity rather than assuming it away.

    Models: random-effects · multilevel · meta-regression · network

  5. 5

    Stress-test

    Assess publication bias, run sensitivity and leave-one-out analyses, and test how robust the pooled estimate is.

    Checks: funnel · Egger · trim-and-fill · leave-one-out

  6. 6

    Report

    Deliver forest and funnel plots, a PRISMA flow diagram, methods and results text, and reproducible code and data.

    Output: forest/funnel plots · PRISMA diagram · methods · R/Stata code

Rigor by default

The checks that decide whether a review holds up

A pooled estimate is easy to produce and easy to attack. The safeguards that make a synthesis credible are standard on every engagement.

Included on every project

  • Pre-specified protocol and inclusion criteria
  • Reproducible search string and PRISMA flow diagram
  • Heterogeneity quantified (I², tau²) and explained
  • Publication-bias assessment and sensitivity analysis
  • Reproducible code and extraction dataset you keep
What You Receive

Every engagement, delivered in full

Not a black-box result and a number, but a complete, documented package you can submit, defend, and reproduce.

  • Registered protocol and reproducible search string
  • Screening records and PRISMA flow diagram
  • Clean, documented effect-size extraction dataset
  • Pooled estimates with heterogeneity statistics
  • Forest, funnel, and moderator plots
  • Publication-bias and sensitivity analysis
  • Interpretation of the pooled effect and its limits
  • Reproducible R (metafor) or Stata code
  • Journal-ready methodology and results sections
Where this fits

Part of a larger arc

A synthesis is strongest when the review design ahead of it is deliberate and the reporting after it is precise—each handled with the same care.

Stage 02 · Design

Research Design & Planning

Identification strategy, power, and specification decided before estimation begins.

Explore methods
Stage 06 · Validate

Statistical & Methodological Audit

An independent check of assumptions, specification, and reproducibility before submission.

Explore audit
Stage 08 · Publish

Publication & Research Support

Methods and results reporting, journal selection, and reviewer-response support.

Explore support
FAQ

Common questions

Answers to what most researchers and project leads ask before we begin a review or meta-analysis engagement.

A systematic review is a structured, reproducible search and appraisal of all evidence on a question; a meta-analysis is the statistical step that pools effect sizes across those studies into a summary estimate. Not every systematic review supports a meta-analysis—when studies are too heterogeneous, a rigorous narrative or scoping synthesis is the honest choice, and we will say so.
Yes. We work to PRISMA reporting standards, and where appropriate we help prepare and register a protocol (for example on PROSPERO or OSF) before screening begins. A pre-specified protocol is what protects the review from the criticism that decisions were made after seeing the results.
We quantify it, then explain it. That means reporting I² and tau², choosing random-effects over fixed-effects where heterogeneity is real, and using meta-regression and subgroup analysis to identify the study-level factors that drive differences in effects, rather than averaging them away.
Yes. We use funnel plots, Egger's and related tests, trim-and-fill, p-curve or selection models, and sensitivity analysis to gauge how far small-study effects or missing null results might be shaping the pooled estimate—and we report the pooled effect's robustness to them.
CoTiMA—continuous-time meta-analysis—pools longitudinal effects measured across studies that used different time lags, by estimating an underlying continuous-time model. It is the right tool when your evidence base is cross-lagged panel studies with varying intervals, where conventional meta-analysis of lag-specific coefficients would be misleading.
Either. We can design and run the full pipeline—search strategy, deduplication, title/abstract and full-text screening, and data extraction—or take a completed, screened dataset and handle the synthesis and modeling. We document each stage so the review is reproducible from the search string forward.
Primarily R (metafor, meta, and related packages) and Stata, with reference-management and screening tools for the review stage. You receive the extraction dataset, versioned analysis code, and a PRISMA flow diagram alongside the results.
Yes, and it is the best time to involve us. Defining the question, inclusion criteria, and effect-size metric up front—and checking that enough comparable studies exist to support a meta-analysis at all—prevents months of screening that ends in a synthesis the data can't support.

Synthesizing a literature?

Tell us the question and roughly how many studies you're working with—we'll tell you whether it supports a meta-analysis, and what the review will take.