The impact of using the web in a mixed mode follow-up of a longitudi- nal birth cohort study: evidence from the National Child Development Study

................................................................................................................................ 2 Introduction ........................................................................................................................... 2 Literature review and research questions .............................................................................. 4 The NCDS study and the sequential mixed mode in its age 55 sweep .................................. 6 Measuring mode effects: the mixed-mode experiment, and methodology for its evaluation .. 7 Balance of experimental groups .......................................................................................... 11 Survey response, compliance status, and non-response .................................................... 11 Evidence of mode effects on participation and on item response and values ...................... 12 Evidence on whether introducing the web brought cost savings .......................................... 13 Conclusions ........................................................................................................................ 14 References ......................................................................................................................... 15 Tables ................................................................................................................................. 18 Figures ................................................................................................................................ 32