NCDS9 (2013)

The age 55 survey ran from September 2013-March 2014. Data collection involved a sequential mixed mode approach whereby cohort members were invited to complete a web survey and those not responding were invited to participate via telephone. More than 9,100 cohort members took part in total, with sixty six per cent doing so online.

This was the first time that web-based data collection has been used on any of the birth cohort studies run by CLS. The survey needed to collect complex data and as such, much work was put in to ensuring that it was easy for cohort members to navigate and provide accurate responses.  In particular, an interactive visual calendar was developed to aid the collection of 'event histories'.

Between September and November 2012 two rounds of ‘usability testing’ for the web questionnaire were conducted with 20 members of the public aged between 50 and 60. Respondents were recorded as they completed the web survey and were also observed and questioned by a researcher. A number of improvements to the questionnaire were made as a result.

A pilot study took place in early 2013, primarily with members of the public recruited into a pilot panel at the time of the Age 50 survey.  Half of those invited to participate did so by completing the web survey.  A sub-sample of web participants were telephoned and asked for feedback about their experience of completing the survey.  In general the feedback received was very positive.  A second pilot with a sub-sample of 240 NCDS cohort members took place between May and June. 

As this is a mixed-mode survey, it was critical that the data collection instruments were designed in such a way as to minimise the potential for differences across the two modes. The main stage of fieldwork included an experiment to examine the potential impact of the mixed mode approach on response rates and comparability of survey estimates. Findings from this work will be beneficial to the design of future sweeps of the birth cohort studies and other longitudinal surveys more generally.

Data from the age 55 survey is now available to download from the UK Data Service.

CLS will carry out a new survey of the NCDS cohort at age 60 in 2018.