If a study were to be performed to determine risk factors for ocular problems with this man's underlying disease, what kind of variable would be used to record demographic information?
Demographic data are recorded as nominal variables. Categorical variables can be nominal or ordinal. A nominal variable is assigned (not measured) and could be a demographic characteristic such as sex or race. An ordinal variable is a ranking, such as mild, moderate, or severe.
What kind of variable would be used to record his laboratory findings from a blood specimen?
Quantitative variables are measured values. A discrete quantitative variable has a finite number of possible measurements. A continuous quantitative variable has an infinite number of possible measurements within a range, as would be typical for a serum chemistry test such as glucose.