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 the United States, even the meaning of life can have a partisan tinge. In February 2021, Pew Research Center asked 2,596 U.S. adults the following open-ended question: “What about your life do you ...