1. Statistical Literacy: a study used the variables: income, job satisfaction, and commute to and from work. How or why could the included variables be confounded? List at least one non-collected variable that could confound all variables.

2. Statistical Literacy: In a completely randomized study a control group received a candy pill disguised as a decongestant and a treatment group received a newly developed decongestant. Describe how this could be made into a double-blinded experiment and the benefits of such experiment.

3. Critical Thinking: An environmental scientist deployed a very well-designed survey at a farmer's market to capture city residents' opinions about recycling; she explained participants that their responses might be used to change the city's garbage collection policies. She stood in front of respondents in a position where they could see her t-shirt reading 'fight climate change'. Do respondents represent a random sample of the city's residents? Would you be concerned that in spite of a well-designed survey, the scientist may introduce bias into respondents' responses? Justify each answer.