Chapter 3 Description of qualitative variable
Quantitative variable Qualitative variable Multiple categorical variable Ordinal variable Binary variable review
qualitative variable also known as categorical or nominal is one that can not be measured in the usual sense , only can be categorized convey information regarding attribute review
Binary variable: gender, live or death, yes or no. Multiple categorical variable blood types race A, B , AB, O white, black, yellow, brown Ordinal variable: there is an order in the categories Your opinion on something: unsatisfactory, normal, very satisfactory review
To keep things simple, we begin with table 1 that shows the relative numbers of a kind of infection disease in a city. Relative number rateproportionratio
1. Count - The number of individuals with the outcome of interest
2. Proportion - The number of individuals(patients) within a defined group(district) divided by the number of individuals enumerated in the population(total of the patient)
a = number who develop disease within a defined group a+b+c+… = total number who develop disease Proportion = a a + b+c+… 0 Proportion 1
3. Rate - The number of individuals within a defined group who develop disease divided by the number of individuals enumerated in the population at risk.
4. Ratio - One number divided by another number
Exercise
Exercise ( answer)