In a study of the effect of playing video games on sleep quality, researchers randomly assigned some participants to play an up-tempo video game for either one or three hours before bed. Other participants had no engagement with electronics in the time before bed. Then, the researchers assessed all the participants' sleep quality (e.g., number of awakenings, percentage of time in deep sleep) during an overnight sleep study. In this experiment, the time spent playing video games (e.g., one or three hours) is the ________.

In research there are different ways to test a hypothesis. One of them is the experiments in which we have one or more factors that can be modified to alter the result.

These factors are known as independent variables because their variation does not depend on other factors. On the contrary, they influence the variation of other factors that are known as dependent variables.

According to the above, it can be inferred that time is the independent variable of this research because its modification is planned to evaluate the different variables that it can cause.

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