Login Registrieren

Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

The Practice of Statistics for AP Examination

Daren Starnes, Josh Tabor

$Math Studyset Vaia Explanations$ Math

6th Edition · 837 pages

ISBN: 9781319113339

Chapter 4: Q. 25 (page 239)

Eating on campus The director of student life at a small college wants to know what
percent of students eat regularly in the cafeteria. To find out, the director selects an SRS of
300 students who live in the dorms. Describe how undercoverage might lead to bias in this
study. Explain the likely direction of the bias.

Short Answer

Expert verified

It is an example of undercoverage because students who do not live in the dorms cannot be a part of sample and it is more likely to shift towards higher percentage side.

Step by step solution

01

Given information

We need to describe how undercoverage might lead to bias in this study.

02

Explanation

It is an example of undercoverage because students who do not live in the dorms cannot be a part of sample. Some students may live off campus and be less likely to eat in cafeteria so the estimate that the director get is more likely to be higher than if the question is asked to the all students.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Killing weeds A biologist would like to determine which of two brands of weed killer, X or Y, is less likely to harm the plants in a garden at the university. Before spraying near the plants, the biologist decides to conduct an experiment using $24$ individual plants. Which of the following two plans for randomly assigning the treatments should the biologist use? Why?

Plan A: Choose the $12$ healthiest-looking plants. Then flip a coin. If it lands heads, apply Brand X weed killer to these plants and Brand Y weed killer to the remaining $12$ plants. If it lands tails, do the opposite.

Plan B: Choose $12$ of the $24$ plants at random. Apply Brand X weed killer to those $12$ plants and Brand Y weed killer to the remaining $12$ plants.

Animal testing (1.1) “It is right to use animals for medical testing if it might save human lives.” The General Social Survey asked $1152$ adults to react to this statement. Here is the two-way table of their responses:

Opinion about using animals for medical testing :

	Male	Female	Total
Strongly agree	$76$	$59$	$135$
Agree	$270$	$247$	$517$
Neither agree nor disagree	$87$	$139$	$226$
Disagree	$61$	$123$	$184$
Strongly disagree	$22$	$68$	$90$
Total	$516$	$636$	$1152$

a. Construct segmented bar graphs to display the distribution of opinion for males and for females. b. Is there an association between gender and opinion for the members of this sample? Explain your answer

iPhonesSuppose $1000$ iPhones are produced at a factory today. Management would like to ensure that the phones’ display screens meet their quality standards before shipping them to retail stores. Because it takes about $10$ minutes to inspect an individual phone’s display screen, managers decide to inspect a sample of $20$ phones from the day’s production.

a. Explain why it would be difficult for managers to inspect an SRS of $20$ iPhones that are produced today.

b. An eager employee suggests that it would be easy to inspect the last $20$ iPhones that were produced today. Why isn’t this a good idea?

c. Another employee recommends a different sampling method: Randomly choose one of the first $50$ iPhones produced. Inspect that phone and every fiftieth iPhone produced afterward. (This method is known as systematic random sampling.) Explain carefully why this sampling method is not an SRS.

You wonder if TV ads are more effective when they are longer or repeated more often

or both. So you design an experiment. You prepare $30$ -second and $60$ -second ads for a

camera. Your subjects all watch the same TV program, but you assign them at random

to four groups. One group sees the $30$ -second ad once during the program; another sees

it three times; the third group sees the $60$ -second ad once; and the last group sees the

$60$ -second ad three times. You ask all subjects how likely they are to buy the camera.

Which of the following best describes the design of this experiment?

a. This is a randomized block design, but not a matched pairs design.

b. This is a matched pairs design.

c. This is a completely randomized design with one explanatory variable (factor).

d. This is a completely randomized design with two explanatory variables (factors).

e. This is a completely randomized design with four explanatory variables (factors).

A louse-y situation A study published in the New England Journal of Medicine compared two medicines to treat head lice: an oral medication called ivermectin and a topical lotion containing malathion. Researchers studied 812 people in 376 households in seven areas around the world. Of the 185 households randomly assigned to ivermectin, 171 were free from head lice after 2 weeks, compared with only 151 of the 191 households randomly assigned to malathion.

a. Calculate the difference (Ivermectin – Malathion) in the proportion of households that were free from head lice in the two groups.

One hundred trials of a simulation were performed to see what differences in proportions would occur due only to chance variation in the random assignment, assuming that the type of medication doesn’t matter. The results are shown in the dotplot.

b. There is one dot at 0.09. Explain what this dot means in this context.

c. Use the results of the simulation to determine if the difference in proportions from part (a) is statistically significant. Explain your reasoning.

See all solutions

Recommended explanations on Math Textbooks

Decision Maths

Read Explanation

Logic and Functions

Read Explanation

Mechanics Maths

Read Explanation

Calculus

Read Explanation

Statistics

Read Explanation

Discrete Mathematics

Read Explanation

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free