A university introduces a new premium meal plan that offers higher-quality food, more menu options, and shorter wait times. The university allows dormitories to decide whether to switch to the new plan. Participation is voluntary, and dorms must actively opt in to adopt the new system. After one semester, the university finds that dorms using the new meal plan report significantly higher student satisfaction scores compared to dorms that kept the old plan. Explain why selection bias might be leading to the wrong conclusion.

Model A uses only GPA and SAT Score as predictors. Model B adds Essay Score (rated 0–10 by reviewers) as an additional predictor. Both models are fit on the same 400 applicants. AIC (Akaike Information Criterion) is used to compare model fit. Model Predictors AIC Model A GPA, SAT Score 491.6 Model B GPA, SAT Score, Essay Score 480.1 Based on the AIC values above, which model should the admissions office prefer, and why? 

A food delivery platform allows a small group of restaurants to offer a “Free Dessert with Every Order” promotion as a pilot test. These restaurants experience a significant increase in order volume compared to other restaurants on the platform. Based on these results, the platform decides to roll out the promotion to all restaurants. Explain why a market effect might lead to a much smaller increase in order volume when the promotion is implemented across all restaurants (external validity issue).

You are testing whether adding a “Limited-Time Discount Banner” on a shopping website increases the average purchase value. Which of these issues might be threatening the internal validity of your experiment? Select ALL that apply.

Interpret the slope coefficient for log(Number of followers)

After running a linear regression, you obtain the following residuals. Which of the L.I.N.E. assumptions are clearly violated:

True or False. This is a sentence fragment:  The child with the bright blue eyes who attends Pleasantville Elementary School

A complete sentence must include a subject, a verb, and _________________. 

The audience listened closely to the speaker.

True or False. This is a sentence fragment:  The children were playing noisily in the backyard and arguing over whose turn it was next.