This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
An investigator into the life expectancy of IV drug abusers divides a sample of patients into HIV positive and HIV negative groups. What type of data does this division constitute ? 
Select and explain. 
A. Nominal, B. Ordinal, C. Interval, D. Poion
A: Nominal
Answer: A: Nominal 
Explanation: Ans. is `a' i.e., Nominal In the question, data has been divided into two groups, i.e. HIV positive/HIV negative Data should be measured on nominal scale especially Dichotomous type of nominal scale.