Both of the above scenarios involve the generation of data: information about observable or measurable phenomena in the world. In the scenario above where effects of carbon and nitrogen are associated with plants’ root structures, data would consist of measurements associated with the roots.
Alternatively, the information collected in the first example—that people in a given group have different hair texture that can be described and grouped by category—is what we usually call qualitative data. Qualitative data is observable or measurable information that is not (typically) numerical in nature.
Writing and Talking about Data: What can we do with it and what should we do with it?