Final answer:
An experimental design examines one variable, while a correlational design looks at the relationship between two variables, often displayed with a line graph.
Step-by-step explanation:
While an experimental design looks carefully at one variable, a correlational design investigates the association between two variables. These associations of variables are often displayed using a line graph.
In an experimental design, researchers typically manipulate the independent variable to observe the effect on the dependent variable. A control group is essential in this design to serve as a basis for comparison, controlling for chance factors that might influence the results of the study by holding such factors constant across groups.
A correlational design, on the other hand, aims to identify whether there is a correlation between two variables. This is quantified by the correlation coefficient, a number from -1 to +1 indicating the strength and direction of the relationship between variables. Line graphs are often utilized to show how one variable changes as the other does, with one measured on the horizontal axis and the other on the vertical axis.