Statistics Question

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Context

In 2015 college students at a large state university completed a survey about their academic and personal life. Questions ranged from “How many credits are you registered for this semester?” to “Would you define yourself as a vegetarian?”

The researcher randomly selected 325 students from the university; 312 responded to the survey.

Variables

• Math: Math SAT score
• Verbal: Verbal SAT score
• Credits: Number of credits the student is registered for
• Year: Year in college (1=Freshman, 2=Sophomore, 3=Junior, 4=Senior)
• Exercise: Time (in minutes) spent exercising in a typical day
• Sleep: Time (in hours) spent sleeping in a typical day
• Veg: Are you a vegetarian (yes, no, some)
• Cell: Do you own a smart phone (yes, no)

Data

Open the cell-phones datafile in the Stats at Cuyamaca College group on StatCrunch ( – opens in a new tab).

Prompt

Here is the research question for this lab.

Based on a recent study, roughly 80% of college students in the U.S. own a smartphone. Is the proportion of smartphone owners lower at this university?

Work through the questions below to identify the information you will need to answer this question.

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Question 12 / 2 pts

What type of study is this?

Observational study

Correct. This is an observational study. The researchers gathered data through a survey.

Experiment

IncorrectQuestion 20 / 2 pts

What is the goal of statistical inference for this study?

estimate a population mean with a confidence interval estimate a population proportion with a confidence interval testing a claim about a population mean with a hypothesis test

Incorrect. The data involves a categorical variable, not a quantitative variable. Therefore, we are not concerned with a population mean in this study.

testing a claim about a population proportion with a hypothesis test

PartialQuestion 30.75 / 2 pts

Identify each variable as either relevant or not relevant to the research question; further classify the relevant variable(s) as either quantitative or categorical.

Relevant; Categorical Verbal

Relevant; Categorical

Credits

Not relevant to the question

Year

Not relevant to the question

Exercise

Relevant; Categorical

Sleep

Relevant; Categorical

Veg

Relevant; Quantitative

Cell

Relevant; Categorical

IncorrectQuestion 40 / 2 pts

Which of the following is the appropriate graph to summarize the data relevant to this question?

Side-by-side boxplots

Incorrect. A boxplot is a visual display of a quantitative variable. We use side-by-side boxplots to compare the distribution of a quantitative variable across multiple groups from a categorical variable. In other words, side-by-side boxplots are a meaningful display when we have a categorical variable and a quantitative variable such as gender (categorical) and wrist-girth (quantitative).

Cell is a single categorical variable.

Scatterplot Two-way table Piechart Histogram

IncorrectQuestion 50 / 2 pts

Which of the following is the appropriate numerical summary of the data relevant to this question?

descriptive statistics such as the mean and standard deviation

Incorrect. We use descriptive statistics such as mean, median, standard deviation, IQR, etc. to describe the distribution of a single quantitative variable across multiple groups of a categorical variable.

Cell is a single categorical variable.

percentages (proportions) Correlation (r) if appropriate Conditional percentages

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