Data types

Epidemiological investigation requires a good understanding of different data types, as this will strongly influence data analysis and interpretation. Data can broadly be classified as qualitative and quantitative, as shown below, although through manipulation, these types can be changed. Within each of these groups, data types can be classified further.

Qualitative data

Qualitative data may be relatively subjectively defined, or are not numerical in nature.

Quantitative data

Quantitative data are expressed numerically.