Lisa Calderwood

Predictors of non-response in a UK-wide cohort study of children's accelerometer-determined physical activity using postal methods

Objectives To investigate the biological, social, behavioural and environmental factors associated with non-consent, and non-return of reliable accelerometer data (≥2 days lasting ≥10 h/day), in a UK-wide postal study of childrens activity. Design Nationally representative prospective cohort study. Setting Children born across the UK, between 2000 and 2002. Participants 13 681 7 to 8-year-old singleton children who were invited to wear an accelerometer on their right hip for 7 consecutive days. Consenting families were posted an Actigraph GT1M accelerometer and asked to return it by post. Primary outcome measures Study consent and reliable accelerometer data acquisition. Results Consent was obtained for 12 872 (94.5%) interviewed singletons, of whom 6497 (50.5%) returned reliable accelerometer data. Consent was less likely for children with a limiting illness or disability, children who did not have people smoking near them, children who had access to a garden, and those who lived in Northern Ireland. From those who consented, reliable accelerometer data were less likely to be acquired from children who: were boys; overweight/obese; of white, mixed or ‘other’ ethnicity; had an illness or disability limiting daily activity; whose mothers did not have a degree; who lived in rented accommodation; who exercised once a week or less; who had been breastfed; were from disadvantaged wards; had younger mothers or lone mothers; or were from households with just one, or more than three children. Conclusions Studies need to encourage consent and reliable data return in the wide range of groups we have identified to improve response and reduce non-response bias. Additional efforts targeted at such children should increase study consent and data acquisition while also reducing non-response bias. Adjustment must be made for missing data that account for missing data as a non-random event.

Using new technologies for time diary data collection : instrument design and data quality findings from a mixed-mode pilot survey

Recent years have witnessed a steady growth of time-use research, driven by the increased research and policy interest in population activity patterns and their associations with long-term outcomes. There is recent interest in moving beyond traditional paper-administered time diaries to use new technologies for data collection in order to reduce respondent burden and administration costs, and to improve data quality. This paper presents two novel diary instruments that were employed by a large-scale multi-disciplinary cohort study in order to obtain information on the time allocation of adolescents in the United Kingdom. A web-administered diary and a smartphone app were created, and a mixed-mode data collection approach was followed: cohort members were asked to choose between these two modes, and those who were unable or refused to use the web/app modes were offered a paper diary. Using data from a pilot survey of 86 participants, we examine diary data quality indicators across the three modes. Results suggest that the web and app modes yield an overall better time diary data quality than the paper mode, with a higher proportion of diaries with complete activity and contextual information. Results also show that the web and app modes yield a comparable number of activity episodes to the paper mode. These results suggest that the use of new technologies can improve diary data quality. Future research using larger samples should systematically investigate selection and measurement effects in mixed-mode time-use survey designs.

Collecting saliva samples for DNA extraction from children and parents: findings from a pilot study using lay interviewers in the UK

In recent years there has been a substantial increase in the collection of biological data on social surveys. Biological data has hitherto been primarily collected by medically trained personnel in a clinic or laboratory setting or using specialist nurse interviewers in a home-visit setting. However, improvements in technology and the development of minimally or non- invasive data collection methods have made it increasingly feasible to collect bio-measures in a home setting using non-medically trained lay interviewers. In the field of genetic research, it has become increasingly common to collect DNA from saliva samples. This paper provides an account of a pilot study investigating the feasibility of collecting saliva samples for DNA extraction from mothers, fathers and children aged around 11 years old using lay interviewers on the UK Millennium Cohort Study. The pilot study was carried out in 2011 in five areas of the UK with one interviewer in each area. 45 families took part in the pilot and saliva samples were obtained from 73 per cent of mothers, 76 per cent of fathers and 74 per cent of children. We demonstrate that it is indeed viable to collect saliva samples for DNA extraction from children and parents using lay interviewers in a home setting, and provide practical suggestions about how the data collection process could be improved in order to achieve higher response rates and improved specimen quality. Our findings are relevant to other surveys planning to incorporate saliva sample collection for DNA extraction, particularly for those involving lay interviewers in a home setting.