Which data type is used to establish an environmental baseline by reviewing existing sources?

• A. Secondary data
• B. Primary data
• C. Experimental data
• D. Anecdotal data

Answer: (A)

Establishing an environmental baseline from existing sources relies on secondary data—the information that already exists and was collected by others for purposes other than your current study. By reviewing government reports, previous monitoring programs, scientific papers, maps, and historical records, you can characterize current or past environmental conditions without conducting new measurements. This approach is efficient and provides a reference point for comparison as you move forward with your assessment. Primary data would involve collecting new measurements specifically for your study, which isn’t what’s described here. Experimental data comes from controlled tests or experiments, and anecdotal data consists of informal, non-systematic observations that aren’t reliable enough on their own for a baseline. So using existing sources to build the baseline points to secondary data.