For each of the following cases (a and b),
(i) state whether the study should be observational or experimental and why.
(ii) state whether blinding should be used. If the study should be run blind or double-blind, who should be blinded and why?
(a) An investigation of whether taking an aspirin every day decreases the chance of having a stroke.
(b) An investigation of whether attending religious services regularly reduces blood pressure.