5, if you are including Trump.
Explanation:
(a) Experimental unit
A person or an object, or some well-defined body or item on which some treatment is applied
(b) Treatment
Combination of a values of factors. These are explanatory variables.
(c) Response variable
The qualitative variable or quantitative variable in which the researcher wants to determine how the value is affected by any explanatory variable.
(d) Factor
It is the variable whose influence on a response variable can be assessed by the researcher.
(e) Placebo
An innocuous treatment, like a sugar tablet, which looks, smells and tastes like an experimental medication.
(f) Confounding
The effect of the two factors cannot be distinguished.
