answering questions related to causality and research design

I have attached a document where you will find most of the information required to answer the questions in the second document. In case you do not find the answer in the document after looking through it completely you may use the internet to find the answer but do rephrase and use your own words and include the sources used.

Please stick to the maximum number of the sentences required in each question. Do not copy paste answers, rephrase them and use your interpretation. Keep your answers simple and straightforward, nothing complex. Please use simple wording that is appropriate to each question.

Thanks for installing the Bottom of every post plugin by Corey Salzano. Contact me if you need custom WordPress plugins or website design.