Theoretical Sampling Design Options for a New Birth Cohort: An Accelerated Longitudinal Design Perspective

Natalie Shlomo, Chris Skinner, Sook Kim

Research output: Working paper


• The key difference between an accelerated longitudinal design and the single cohort study is that an accelerated longitudinal design incorporates multiple cohort groups at the onset of the study, enabling the duration of the study to be shortened. This investigation focuses on aspects of an accelerated longitudinal design compared to a single cohort design, particularly for following babies, children and youth into adulthood. We provide a comprehensive literature review and investigate aspects of the designs through a theoretical assessment and simulation study.

• The theoretical assessment of the precision of basic longitudinal analyses under single, 2-cohort and 3-cohort designs shows that sample sizes can be compromised especially at the extreme ages of the cohorts. This problem can be addressed by refreshment samples that not only ensure representativity but also compensate for left- censored data.

• The simulation study shows that the accelerated longitudinal designs permit analysis across a wider age span for a given duration of the study. The precision of parameter estimation for a multilevel growth curve model is similar for the alternative designs. If cohort effects are present in the study, it is important to include cohort main effects and their interactions in the model. For small sub-groups, the level of precision can be compromised due to small sample sizes.

• The overall conclusion of this investigation regarding the suitability of an accelerated longitudinal design for the future of longitudinal study in the UK is positive. We recognize, nevertheless, that, in coming to a decision about the longitudinal design, careful consideration is needed of the different types of analysis undertaken by substantive researchers and their additional complexities under an accelerated longitudinal design. In addition, it may be important to consider other aspects of survey methodology impacted by an accelerated longitudinal design when coming to a decision, but these are outside the scope of this report.

• From the review of international surveys of children and young people, it is clear that multiple cohort designs have been successfully implemented in different countries and the UK can learn from such experiences whilst considering specific needs, for example, boosting the 2016 ‘missed’ cohort from the cancelled Life Style Study.
Original languageEnglish
Place of PublicationSwindon
PublisherEconomic and Social Research Council
Number of pages39
Publication statusUnpublished - 1 Aug 2019


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