Daniel Okafor, PhD, MS
Senior Researcher, Biostatistics
Daniel Okafor leads the Initiative's statistical methods program. His work centers on agreement statistics for dietary assessment (limits of agreement, intraclass correlation, equivalence testing) and on the design of validation studies for image-based food recognition. PhD in Biostatistics; MS in Nutritional Sciences.
Areas of work: Agreement statistics; Bland-Altman analysis; Equivalence testing; Sample size methodology
Joined the Initiative: 2023-11
ORCID: 0000-0001-7263-4419
Publications
- Independent validation of six commercial AI-assisted dietary assessment applications against weighed-food reference: a 180-meal cross-sectional study (2026)
- Photo-based vs. manual-entry dietary assessment: a meta-analysis of accuracy differentials (2026)
- Independent validation of image-based dietary assessment applications: a systematic review and meta-analysis (2018-2024) (2025)
- Equivalence testing in nutritional epidemiology: when 'no significant difference' is not enough (2025)
- Mean absolute percentage error versus absolute kilocalorie error in dietary assessment validation: when does normalisation matter? (2025)
- Vendor-reported accuracy claims for image-based dietary assessment applications: a systematic review of methodology gaps (2024)
- Bland-Altman analysis for dietary assessment validation: conventions, common errors, and recommended reporting (2024)
Preprints
- Within-application accuracy gaps between manual-entry and photo-based modes in a single dietary tracking application: a focused replication (2026)
- When Bland-Altman limits of agreement and intraclass correlation rank dietary assessment apps differently (2025)
Methodology briefs
- Pre-specifying equivalence margins for dietary assessment non-inferiority claims (2026)
- Re-rating concordance protocol: blinded sub-sample re-evaluation for single-rater validation studies (2025)
- Sample-size considerations for image-based dietary assessment validation studies (2025)
- Reporting MAPE in dietary assessment: rounding, thresholds, and confidence intervals (2024)
- Limits of agreement: how we report Bland-Altman intervals in Initiative validation work (2024)
Commentary
- Responding to vendor feedback on our six-application validation study (2026)
- Pre-registration log: the six-application validation study (DAI-VAL-2026-01) (2026)
- The 95% confidence interval problem in mobile app marketing claims (2025)
- A correction to our 2024 systematic review: vendor-reported MAPE definition (2025)