“You are a data scientist of an e-commerce platform. You are debating with your colleague whether it is better to use observational data or experimental methods to test the effectiveness of a marketing campaign. Your colleague argues that it is better to use observational data versus you think it is better to use experimental method. Specifically, your colleague said that observational data is better because of the high external validity, meaning that it is more generalizable. Try to provide counterarguments against your colleague’s argument”