Imagine you're a researcher studying how sleep affects mood. To explore the connection, you would look at two key "variables": sleep (how much someone gets) and mood (how happy or irritable they feel) ...

In science, a variable is something that can be changed, measured or controlled in an experiment. Scientists look at variables to understand how they affect things. A variable is any one of the things ...

Time-dependent variables can be used to model the effects of subjects transferring from one treatment group to another. One example of the need for such strategies is the Stanford heart transplant ...