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.
The definition of observational science is a field of science where controlled observations cannot be done in order to study causes and effects. Scientific studies are simply done through the observation of nature taking its course and recording the findings over time. Astronomy.