Qualitative Versus Quantitative
Variables are classified as either qualitative or quantitative:
- A qualitative variable categorizes cases (e.g., diabetic status: yes/no, type of diabetes)
- A quantitative variable records numerical measurements (e.g., blood glucose levels, BMI, HbA1c %)
Diabetes Analysis
If cases are individual patients:
Patient diabetic status (yes/no) is qualitative classification
If cases are US states:
Diabetes prevalence rates (%) are quantitative measurements
Variable Manipulations
Can use numbers to code categories of qualitative variables.
- e.g., Gender (0 for male and 1 for female).
Can convert quantitative variables into qualitative groups.
- e.g., Income (0-50000 as Low, 50000+ as High).