First you will analyze the study design. (a) What is the purpose of the study? What is the response variable? What are the explanatory variables? (b) How were those subjects in the study selected? Can you generalize the results of the study to any well-defined population? What do you think was the reason of selecting students with either low or high full-scale IQs? (c) Can the study be used to demonstrate a causal relationship between brain size and cognitive ability measured by PIQ? Provide brief explanations. Except for gender and brain size, what are other possible variables that may have an effect on performance IQ score of a subject? How can you control some of the variables