Secondary data

Secondary data come from existing sources. Census results can provide population information; maps can help identify locations; older photographs can provide evidence of earlier conditions; and council documents or newspaper reports can help explain why regeneration took place. Secondary data can support an enquiry, but using them is not compulsory in every enquiry.

Secondary data is information collected or produced by someone else. Your measurements describe river conditions at particular sites and times. Secondary evidence can place those observations within a wider picture of the catchment and its flood risk.

Eurostat, the statistical office of the European Union, publishes secondary data that can be used to investigate international links. Its figures allow you to compare changes over time, but you first need to identify exactly what each series measures.

Secondary data come from existing sources, such as published weather records, maps or information about a regeneration project.