A conservation biologist is investigating the impact of a newly constructed bypass road on the health of a local river ecosystem. To do this, she visits five specific sites along the river and uses a digital probe to measure the dissolved oxygen concentration (in mg/L) at each location. She also obtains historical monthly water temperature and rainfall records for the area over the past 10 years from the Meteorological Office's public archives.
Referring to this study, explain the difference between primary and secondary data.
235 exam-style questions on AQA A Level Psychology Data handling and analysis. Each one has a worked solution and a mark scheme showing where the marks go.