NSAIDs interact with the endocannabinoid system and its endocannabinoids, as COX2 have been shown to utilize endocannabinoids as substrates, and may have a key role in both the therapeutic and adverse effects of NSAIDs, as well as in NSAIDs-induced placebo responses.
Definition: An independent variable is the variable that is changed or controlled in a scientific experiment. Independent variables are the variables that the experimenter changes to test their dependent variable.
My formal (but open to improvement) definition of 'science': A science is a method, a set of rules using fact and logic, for evidence gathering and testing truth claims in a given field of inquiry, rules which are publicly usable (i.e., neutrally applied to all participants), and which can reasonably be said to lead to the truth of that particular area.