Methodological considerations for the quantification of self-reported caffeine use

Psychopharmacology (Berl). 2009 Apr;203(3):571-8. doi: 10.1007/s00213-008-1403-5. Epub 2008 Nov 15.


Rationale: The field of research regarding the effects of habitual caffeine use is immense and frequently utilizes self-report measures of caffeine use. However, various self-report measures have different methodologies, and the accuracy of these different methods has not been compared.

Materials and methods: Self-reported caffeine use was estimated from two methods (a retrospective interview of weekly caffeine use and a 7-day prospective diary; n = 79). These estimates were then tested against salivary caffeine concentrations in a subset of participants (n = 55).

Results: The estimates of caffeine use (mg/day) from the interview- and diary-based methods correlated with one another (r = 0.77) and with salivary caffeine concentrations (r = 0.61 and 0.68, respectively). However, almost half of the subjects who reported more than 600 mg/day in the interview reported significantly less caffeine use in the diary.

Conclusions: Self-report measures of caffeine use are a valid method of predicting actual caffeine levels. Estimates of high caffeine use levels may need to be corroborated by more than one method.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Caffeine / administration & dosage*
  • Caffeine / analysis
  • Data Collection / methods*
  • Habits*
  • Humans
  • Middle Aged
  • Retrospective Studies
  • Saliva / chemistry
  • Self Disclosure*
  • Surveys and Questionnaires
  • Young Adult


  • Caffeine