An experimental study is conducted examining the relationship between sleep deprivation and depression. participants are kept awake by the experimenters for different amounts of time, and then are assessed on various symptoms of depression. in this study, the number of hours that a participant stays awake is the

I believe the answer is: independent variable

Independent variable is the type of variables which would be influenced by the control group that handled by the researchers. In every research Independent variable represent the things that the researchers want to measures through correlation with other factors.

answer; direct observation;

answer the first monday in december;