Sample size needed depends on effect size. If there's a disease that has resulted in death within a year in every recorded case (assume its a common disease for

Sample size needed depends on effect size. If there's a disease that has resulted in death within a year in every recorded case (assume its a common disease for the sake of argument) in history and your pill cures 2 out of the 7 people in your study? Damn, you've got a fantastic pill there! My favourite example is if you have a pill you think allows people to fly and you administer it to 1 random person and they shoot off into the sky? Despite sample size 1 that's actually pretty strong evidence :D