Dr. Chris Grace describes the principles of correlation and causation. He shares a number of ways that observation is used to collect data. Dr. Grace goes on to explain how experimentation can be used to isolate specific variables and determine whether a correlation is related causally.
View the full class here: https://www.youtube.com/playlist?list=PLVHY3HvnI6yMIotukmARTlrCk2q8RXCHg