Data, Variables, and Types of Data
What is a variable?
Variables explained
A variable is a characteristic that can change from one person, object, or observation to another. Examples include height, age, favorite color, and test score.
Types of variables
Quantitative
- Measured with numbers
- Examples: height, income, temperature
Qualitative
- Describes categories or labels
- Examples: eye color, brand, type of pet
Discrete and continuous
Quantitative data can be discrete, meaning it takes countable values such as number of siblings, or continuous, meaning it can take any value in an interval such as height or time.
Examples of data types
| Data type | Example |
|---|---|
| Quantitative discrete | Number of books |
| Quantitative continuous | Time to finish a race |
| Qualitative nominal | Blood type |
| Qualitative ordinal | Survey rating |
A useful habit
Always ask: Is this value a number that measures size, or is it a label that names a category?
Which is an example of qualitative data?
Favorite movie genre is a category, so it is qualitative.
Correct answer: Favorite movie genre
What makes a variable different from a constant?
Statistics often studies how variables vary across observations.
Correct answer: A variable can change, while a constant stays the same.
Which is discrete data?
Number of pets is counted in whole numbers, so it is discrete.
Correct answer: Number of pets
Give one example of continuous data.
Continuous data can take many values, including decimals.
Correct answer: Examples include height, weight, or time.