New Tool Reliably Measures How Much THC People Actually Consume | Research

The takeaway

The Cannabis Exposure Inventory (CEI) demonstrated substantial test-retest reliability for measuring milligrams of THC consumed per using day, filling a critical gap in cannabis research that has historically measured only frequency, not quantity.

Cannabis researchers, clinicians assessing patient cannabis use, epidemiologists, and policy researchers needing accurate consumption measures.

What the researchers found

The self-administered CEI showed substantial overall reliability for mean mgTHC/using day (ICC=0.77), with consistent performance across demographic subgroups (ICCs 0.54-0.86), use motivations (ICCs 0.69-0.77), and state legalization contexts (ICCs 0.70-0.92).

Why it matters

For decades, cannabis research has measured 'how often' but not 'how much' — this validated tool allows researchers and clinicians to quantify actual THC exposure, which is essential for understanding dose-response relationships.

The numbers in context

N=511; overall ICC=0.77; Hispanic ICC=0.86; 'other' race ICC=0.54; medical-only ICC=0.72; recreational-only ICC=0.69; medical+recreational ICC=0.77; binary measures mean kappa=0.74 (30-day), 0.73 (7-day)

How the study worked

Test-retest reliability study of 511 participants recruited through social media and research panels, completing initial and retest CEI surveys measuring THC milligrams per using day, with Intraclass Correlation Coefficients and kappa statistics for binary measures.

What this study cannot tell us

Self-report measure subject to recall bias; online recruitment may not represent all users; THC content estimates depend on product labeling accuracy; moderate ICC in some subgroups; does not capture other cannabinoids.

How to read the evidence

Well-designed reliability study with adequate sample size and comprehensive subgroup analyses, establishing the psychometric foundation for a needed measurement tool.

When this study was published

Published 2026; addresses a long-standing measurement gap in cannabis research.

The bigger picture

As cannabis products become more varied and potent, having a reliable self-report measure of THC quantity consumed is essential for advancing our understanding of cannabis benefits and harms.

Questions still open

Would the CEI perform as well in clinical settings? How does self-reported THC exposure compare to biomarker-based measures? Can this tool be adapted to measure CBD and other cannabinoid exposure?

Common questions

How can we measure how much THC someone uses?

The Cannabis Exposure Inventory (CEI) is a new self-report tool that calculates milligrams of THC per using day by accounting for different products, methods, and frequencies — showing substantial reliability (ICC=0.77) in testing.

Why does measuring THC quantity matter?

Most cannabis research only asks how often people use, not how much THC they consume. Since products range from low-potency to extremely concentrated, frequency alone can't capture actual exposure — which is key to understanding health effects.

Read the original research

Test-retest reliability of mgTHC consumption in the self-administered Cannabis Exposure Index (CEI).

Drug and alcohol dependence, 279, 113028

View on PubMed ↗Publisher’s paper ↗

Citation

Hasin, Deborah S; Borodovsky, Jacob; Wall, Melanie; Habib, Mohammad I; Murphy, Eilis; Liu, Jun; Stohl, Malki; Struble, Cara A; Livne, Ofir; Greenstein, Eliana; Aharonovich, Efrat; Wisell, Caroline G; Budney, Alan J. (2026). Test-retest reliability of mgTHC consumption in the self-administered Cannabis Exposure Index (CEI).. Drug and alcohol dependence, 279, 113028. https://doi.org/10.1016/j.drugalcdep.2026.113028