What does it mean to say a study has a "dependent variable"?

Saying that a study has a "dependent variable" refers to the aspect of the study that the researcher is measuring to observe the effects of changes in another variable, which is typically called the independent variable. The dependent variable is expected to change as a result of the manipulation of the independent variable, making it crucial for assessing the outcomes of the research.

In a well-designed study, researchers will manipulate the independent variable to see how it impacts the dependent variable, thereby allowing them to establish relationships between the two. For example, if a study aims to find out how different amounts of sleep affect cognitive performance, cognitive performance would be the dependent variable while sleep amount is the independent variable.

Other options suggest characteristics that do not accurately define what a dependent variable is. For instance, describing a dependent variable as independent of changes in other variables contradicts its nature, and stating that it remains constant throughout the study does not capture how it is meant to vary in response to the independent variable. Similarly, while external factors might influence the dependent variable, they are not part of its fundamental definition.