Match the terms with their definitions.
 quantitative data
 qualitative data
 observation
 control
 1. 
 A variation of the experiment in which the independent variable is not changed. It is used as a tool for comparison.
 2. 
 Data that represents quantity; numeric data.
 3. 
 Data that represents qualities or characteristics that can't be expressed by a number.
 4. 
 The act of noting or perceiving objects or events using one or more of the five senses.