Qualitative Data

Qualitative data are data for which the scale of measurement is a set of unordered categories called a nominal scale. For example, types of trees, types of compounds, etc. Qualitative variables are considered discrete variables, because they vary in some quality but not magnitude--one category is not greater than the other.

Qualitative data are based on observations that do not lend themselves to numerical measures. They often call on scientists to make judgments about data. Qualitative data can be a record of differences in qualities, such as color change of a solution or the vitality of a plant over time. These kinds of data may be recorded in a table. Or qualitative data can be pictorial, such as a cell seen through a microscope or the petal structure of a flower. These kinds of data may be recorded in drawings or photographs.