This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
Which of the following variabls is measure on ordinal scale- 
Select and explain. 
A. Type of anemia, B. Severity of anemia, C. Hemoglobin, D. Serum ferritin
B: Severity of anemia
Answer: B: Severity of anemia 
Explanation: Scales can be: Qualitative: Categorical scales: Nominal : eg: names of countries . Dichotomous : eg: yes/no, presence/absence. Ordinal : severity of disease: mild/moderate/severe.eg: staging of cancer, kuppusamy socioeconomic class. Quantitative: Metric scales: Interval Ratio