Dispelling Myths about Randomisation
(bps.org.uk)
When we are interested in cause and effect relationships (which is much of the time!) we have two options: We can simply observe the world to identify associations between X and Y, or we can randomise people to different levels of X and then measure Y.
When we are interested in cause and effect relationships (which is much of the time!) we have two options: We can simply observe the world to identify associations between X and Y, or we can randomise people to different levels of X and then measure Y.