What does the margin of error tell us about a sample taken from a large population? How does the confidence level for a sample outcome differ from the sample’s margin of error? What is a null hypothesis in causal research and what does it mean to say that a study has failed to reject the null hypothesis? How do randomized, prospective and retrospective studies differ from one another? What are the major advantages and disadvantages of each type of study? Each question must be at least 250 words with at least one scholarly source with it.