Longitudinal
Surveys
Longitudinal
surveys, or panels, are where a sample of individuals give data over a period of time. One-off
surveys are called 'cross-sectional' - they provide a snap shot
at a particular point in time. Longitudinal surveys
provide a picture of change over time in a controlled manner by
using the sample group of individuals:
Issues to Consider
- Selection of initial sample is crucial -
since it will be used over a period of time.
- Results can be more
'accurate' - the same group of people are contacted and so
variation due to using different samples is removed
- Attrition - drop-outs from
the panel need to be kept to a minimum. When and how
do you replace drop-outs from the panel?
- Tracing Respondents -
approximately 10% or households move house each year.
Keeping track of these movements is key.
- Incentives - these are very
useful in maintaining panel and ensuring compliance
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