A variable is

A variable is

• A. A constant across all individuals
• B. A characteristic possessed by everyone in the population in varying amounts or kinds
• C. A measure that never changes
• D. A fixed attribute per person

Answer: (B)

A variable is something that can take different values across people or over time. It isn’t the same for everyone, and it isn’t inherently unchanging. The best choice captures that every person has the characteristic, but the value of that characteristic varies from person to person (and can change over time in some cases). For example, age or income are variables because different individuals have different ages or incomes. The other descriptions imply things that don’t vary: a constant across all individuals, a measure that never changes, or a fixed attribute per person. Those ideas don’t fit a variable, since the essence of a variable is its capacity to differ among individuals or over time.

A variable is something that can take different values across people or over time. It isn’t the same for everyone, and it isn’t inherently unchanging. The best choice captures that every person has the characteristic, but the value of that characteristic varies from person to person (and can change over time in some cases). For example, age or income are variables because different individuals have different ages or incomes.

The other descriptions imply things that don’t vary: a constant across all individuals, a measure that never changes, or a fixed attribute per person. Those ideas don’t fit a variable, since the essence of a variable is its capacity to differ among individuals or over time.