Statistical review for mixed and multilevel models
Mixed models are easy to fit and easy to misreport. We check the random-effects structure, the centering, and the reporting that reviewers ask about first.
What we check
- Random-effects structure: which intercepts and slopes, why, and what happened when the model was simplified
- Convergence warnings and singular fits, and whether they are disclosed
- ICC and variance components reported and interpreted
- Centering of predictors (grand-mean versus within-cluster) and how that changes what each coefficient means
- Sample size at each level, and cluster counts relative to the number of random effects
- Estimation and comparison: REML versus ML, and how degrees of freedom or p-values are obtained
- Missing data handling and whether it suits longitudinal or clustered data
- Assumption checks at each level, effect sizes (such as marginal and conditional R-squared), and software, package, and formula reporting
What you get
- A structured report with each issue tied to its page and table, why it matters, and a suggested fix.
- Confirmation of what passed, so you can show a reviewer the checks were run.
- Typically a Tier 2 (Moderate) review. Your quote is a flat price set before any work starts.
What a finding looks like
Illustrative example, not from a client report.
Random slope dropped without reporting a singular fit
Methods, p. 9
The final model has a random intercept only, but the text does not say the maximal model failed to converge or was singular.
Suggested fix
Report the attempted structure, the warning, and the simplification steps, and say how the fixed-effect conclusions change, if at all.
Good to know
We review the analysis and reporting you send. We do not re-run your models unless that is agreed in the quote, and a re-analysis is a separate, larger scope. Pricing is tiered by the complexity of the analysis and quoted flat within 72 hours; nothing starts until you approve it. Your files are used only for the agreed engagement; see our confidentiality approach.
Ready when you are
Tell us about your project and you will get a scoped, flat-price quote within 72 hours.