Methods |
Collection of duplicate diet sample and direct analysis |
Objective observation by trained staff at the household level |
Subjective measure using open-ended questionnaires administered by a trained interviewer |
Subjective measure using open-ended, self-administered questionnaires |
Subjective measures using open- and closed-ended questionnaires administered by a trained interviewer |
Subjective measure using a predefined, self- or interviewer-administered format |
Collected date |
Actual intake information throughout a specific period |
Actual intake information throughout a specific period |
Actual intake information over the previous 24 hours |
Actual intake information throughout a specific period |
Usual intake estimates over a relatively long period |
Usual intake estimates over a relatively long period (e.g., 6 months or 1 year) |
Strengths |
Measurement of dietary exposures possible (e.g., envi ronmental contaminants) |
Ease of application among those with low literacy or those who prepare most meals at home |
Provides detailed intake data; relatively small respondent burden (literacy not required) |
Provides detailed intake data; no interviewer required; no recall bias |
Assesses usual dietary intake |
Assesses usual dietary intake simply; cost-effective and time-saving; suitable for epidemiological studies |
Limitations |
Not suitable for large-scale studies |
Individual dietary consumption not accurate; Not suitable among those frequently eat outside the home |
Possible recall bias; trained interviewer required; possible interviewer bias; expensive and time-consuming; multiple days required to assess usual intake; possible changes to diet if repeated measures |
Relatively large respondent burden (literacy and high motivation required, possible under-reporting); expensive and time-consuming; multiple days required to assess usual intake; possible changes to diet if repeated measures |
High cost and time-consuming; not suitable for epidemiological studies |
Specific to study groups and research aims; uses a closed-ended questionnaire; low accuracy (recall bias); requires accurate evaluation of developed questionnaires |