Not for the purpose of establishing whether there is a negative correlation between smoking and life expectancy.
Also that comic is saying that adding a third variable does not always make the model better. Also p-hacking is a thing. It’s the opposite of what you’re trying to establish, which is the existence of a third variable which improves the model. And once again, I will say that if you find two correlated variables confusing, adding a third variable is NOT going to help you.
Not for the purpose of establishing whether there is a negative correlation between smoking and life expectancy.
Also that comic is saying that adding a third variable does not always make the model better. Also p-hacking is a thing. It’s the opposite of what you’re trying to establish, which is the existence of a third variable which improves the model. And once again, I will say that if you find two correlated variables confusing, adding a third variable is NOT going to help you.