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Directions

Question 1

Answer the following questions in 1-2 sentences

Part A Briefly describe the statistical framework. In particular, what is a parameter, what is a statistic, and how are these two related to one another?

Part B What two things do a distribution tell us about a variable?

Part C Explain why most times it is not practical to conduct a census.

Part D Explain the difference between random sampling and random assignment. What type of claim does using random assignment allow us to make?

Part E Explain what makes an experiment different from an observational study.

Part F: Explain why random assignment allows us to make causal claims.

Question 2

A survey of incomes for 1000 individuals with graduate degrees in business was conducted five years following graduation, the distribution of which is demonstrated in the box plot below.

# 5 number summary and mean
df %>% pull(x) %>% summary 
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   51662   76283   89047  102449  120362  234359
# std.dev
df %>% pull(x) %>% sd()
## [1] 38490.08

Part A: Use the histogram to describe this variable in a complete sentence as we learned in class. Make sure to include context.

Part B: Explain the concept of robustness as it applies to using statistics for describing a variable.

Question 3

The table below presents the results from the 2006 General Social Survey conducted by the National Opinion Research Center polling 1,009 respondents on their age and level of job satisfaction. Row totals have been added in the last column.

For the questions below, you do not need complete sentences but you must show the calculations used to derive your answer

Age
Job Satisfaction
Total
Low Medium High Sum
<30 34 53 88 175
30-50 80 174 304 558
>50 29 75 172 276

Part A: What percentage of all respondents were between 30-50 years old and indicated that they had low job satisfaction?

Part B: Of those responsdents who were between 30-50 years old, what proportion indicated they had low job satisfaction.

Part C: Of those responsdents who had low job satisfaction, what proportion were between 30-50 years old?

Part D: Which age demographic had the highest proportion of respondents indicate that they had high job satisfaction?

Part E: Sketch a graphic/chart to display your results for Part D.

Question 4

A study is designed to test the effect of light level and noise level on exam performance of college students. The light treatments considered are fluorescent overhead lighting, yellow overhead lighting, no overhead lighting (only desk lamps). The noise treatments considered are no noise, construction noise, and human chatter noise.

The researcher contacted a local college and 200 students volunteered to participate in the study. These students were randomly assigned to the treatments.

Part A: Is this an experiment or an observational study? Explain your answer.

Part B: What is an experimental unit in this study?

Part C: How many factors are considered in this study? Identify them, and describe their levels.

Part D: Does this study employ random sampling? Explain your answer.

Part E: Are the results of this study generalizable to all college students? Explain your answer.

Part F: Can we draw causal conclusions from the results of this study? Explain your answer.