Evidence - Quantitative observational studies

There are instances where an experimental study design is inappropriate, so observational studies are used instead. Observational studies do not have an experimental intervention. They rely on the observation of people without full randomisation. These types of studies can inform cause and effect associations and can be applied to existing data sets. Types of observational studies include:

  • before-and-after study
  • case-control study
  • cohort study
  • correlation study
  • cross-sectional study
  • interrupted time series

Visit NICE's website for more information on scientific evidence.