I can think of 2 research questions: 1. Does adding an air filter in peoples home improve health outcomes? 2. Does pumping a suspected noxious element into a r

I can think of 2 research questions: 1. Does adding an air filter in peoples home improve health outcomes? 2. Does pumping a suspected noxious element into a room in lab harm some small group of people in some limited testable way? Question 1 is better than 2. Why? Because there are more people like those in question 1. Answers to question 1 inform my future choices, answers to question 2 do not. I prefer answers that improve health to those that harm health. Always prefer observational studies done in the field (in situ). Demanding experimental studies done in a lab will give you less bang for your buck. Let's all do our part to drive down health care costs, please.