Researchers interested in how sleep deprivation affected performance randomly assigned participants to groups that had one, two, or three nights of sleep deprivation. Then they tested their reaction times on a standard motor reaction task. The dependent variable in this experiment was

Reaction time of the three groups on the standard motor reaction task.

Explanation: Mathematical experiments are made up of two main variables; The dependent and independent variables.

The dependent variable is the variable to be measured in an experiment, The measured or estimated values derived from the dependent variable depends on the values of the independent variable.

In the instance above, the independent variables are the assigned groups from which the reaction time is measured on a standard motor, Thus the obtained values are the dependent variables.