Objectives: To describe the development of the Oxford WebQ, a web-based 24 h dietary assessment tool developed for repeated administration in large prospective studies; and to report the preliminary assessment of its performance for estimating nutrient intakes. Design: We developed the Oxford WebQ by repeated testing until it was sufficiently comprehensive and easy to use. For the latest version, we compared nutrient intakes from volunteers who completed both the Oxford WebQ and an interviewer-administered 24 h dietary recall on the same day. Setting: Oxford, UK. Subjects: A total of 116 men and women. Results: The WebQ took a median of 12?5 (interquartile range: 10?8-16?3) min to self-complete and nutrient intakes were estimated automatically. By contrast, the interviewer-administered 24 h dietary recall took 30 min to complete and 30 min to code. Compared with the 24 h dietary recall, the mean Spearman's correlation for the 21 nutrients obtained from the WebQ was 0?6, with the majority between 0?5 and 0?9. The mean differences in intake were less than 610 % for all nutrients except for carotene and vitamins B 12 and D. On rare occasions a food item was reported in only one assessment method, but this was not more frequent or systematically different between the methods. Conclusions: Compared with an interviewer-based 24 h dietary recall, the WebQ captures similar food items and estimates similar nutrient intakes for a single day's dietary intake. The WebQ is self-administered and nutrients are estimated automatically, providing a low-cost method for measuring dietary intake in large-scale studies.

UK Biobank is an open access prospective cohort of 500 000 men and women. Information on the frequency of consumption of main foods was collected at recruitment with a touchscreen questionnaire; prior to examining the associations between diet and disease, it is essential to evaluate the performance of the dietary touchscreen questionnaire. The objectives of the present paper are to: describe the repeatability of the touchscreen questionnaire in participants (n 20 348) who repeated the assessment centre visit approximately 4 years after recruitment, and compare the dietary touchscreen variables with mean intakes from participants (n 140 080) who completed at least one of the four web-based 24-h dietary assessments post-recruitment. For fish and meat items, 90 % or more of participants reported the same or adjacent category of intake at the repeat assessment visit; for vegetables and fruit, and for a derived partial fibre score (in fifths), 70 % or more of participants were classified into the same or adjacent category of intake (κweighted > 0·50 for all). Participants were also categorised based on their responses to the dietary touchscreen questionnaire at recruitment, and within each category the group mean intake of the same food group or nutrient from participants who had completed at least one web-based 24-h dietary assessment was calculated. The comparison showed that the dietary touchscreen variables, available on the full cohort, reliably rank participants according to intakes of the main food groups.

The judgment mechanisms underlying personal-and group-level ratings of discrimination and privilege were investigated in high-and low-status groups. A consistent personal-group discrepancy is found for discrimination and privilege but is not due to personal differentiation from the group. Instead, personal and group ratings are based on different comparison standards and levels of self (personal vs. social identity); personal motives influence personal ratings, and social motivations influence group ratings. This analysis is supported by contrasting the traditional discrepancy score with a direct comparison measure (Study 2) and by showing the sensitivity of group ratings (but not personal ratings) to group audience and degree of group identification (Studies 3 and 4). Studying the different meanings communicated with personal and group ratings provides more insight into the dimensions of deprivation than do analyses of discrepancy scores.When members of subordinate or devalued social groups make judgments about the discrimination they personally experience, they consistently report lower levels of discrimination than when making such judgments for their group as a whole (Crosby, 1982;D. M. Taylor, Wright, & Porter, 1994). This personal-group discrimination discrepancy is robust, having been observed in many different disadvantaged groups (D. M. Taylor, Wright, Moghaddam, & Lalonde, 1990). In our research we show that the discrepancy is not the result of participants' intentional differentiation from other members of their group as has been assumed. We demonstrate that the personal and group ratings are the result of two distinct types of comparative judgments.The consensus in the literature is that the discrepancy itself indicates that people feel less disadvantaged than their group. This interpretation of the personal-group discrepancy has raised a number of serious questions and concerns (e.g., Crosby, Pufall,

The Oxford WebQ is an online 24-hour dietary questionnaire that is appropriate for repeated administration in large-scale prospective studies, including the UK Biobank study and the Million Women Study. We compared the performance of the Oxford WebQ and a traditional interviewer-administered multiple-pass 24-hour dietary recall against biomarkers for protein, potassium, and total sugar intake and total energy expenditure estimated by accelerometry. We recruited 160 participants in London, United Kingdom, between 2014 and 2016 and measured their biomarker levels at 3 nonconsecutive time points. The measurement error model simultaneously compared all 3 methods. Attenuation factors for protein, potassium, total sugar, and total energy intakes estimated as the mean of 2 applications of the Oxford WebQ were 0.37, 0.42, 0.45, and 0.31, respectively, with performance improving incrementally for the mean of more measures. Correlation between the mean value from 2 Oxford WebQs and estimated true intakes, reflecting attenuation when intake is categorized or ranked, was 0.47, 0.39, 0.40, and 0.38, respectively, also improving with repeated administration. These correlations were similar to those of the more administratively burdensome interviewer-based recall. Using objective biomarkers as the standard, the Oxford WebQ performs well across key nutrients in comparison with more administratively burdensome interviewer-based 24-hour recalls. Attenuation improves when the average value is taken over repeated administrations, reducing measurement error bias in assessment of diet-disease associations.

Although dietary intake over a single 24-h period may be atypical of an individual's habitual pattern, multiple 24-h dietary assessments can be representative of habitual intake and help in assessing seasonal variation. Web-based questionnaires are convenient for the participant and result in automatic data capture for study investigators. This study reports on the acceptability of repeated web-based administration of the Oxford WebQ -a 24-h recall of frequency from a set food list suitable for self-completion from which energy and nutrient values can be automatically generated. As part of the UK Biobank study, four invitations to complete the Oxford WebQ were sent by email over a 16-month period. Overall, 176 012 (53 % of those invited) participants completed the online version of the Oxford WebQ at least once and 66 % completed it more than once, although only 16 % completed it on all four occasions. The response rate for any one round of invitations varied between 34 and 26 %. On most occasions, the Oxford WebQ was completed on the same day that they received the invitation, although this was less likely if sent on a weekend. Participants who completed the Oxford WebQ tended to be white, female, slightly older, less deprived and more educated, which is typical of health-conscious volunteer-based studies. These findings provide preliminary evidence to suggest that repeated 24-h dietary assessment via the Internet is acceptable to the public and a feasible strategy for large population-based studies.