Stronger players A football coach hears that a new exercise program will increase upper-body strength better than lifting weights. He is eager to test this new program in the off-season with the players on his high school team. The coach decides to let his players choose which of the two treatments they will undergo for3weeks—exercise or weight lifting. He will use the number of push-ups a player can do at the end of the experiment as the response variable. Which principle of experimental design does the coach’s plan violate? Explain how this violation could lead to confounding.

Short Answer

Expert verified

The principle of random assignment is violated, and this could lead to confounding because the players can have the same characteristics and it will affect the results.

Step by step solution

01

Given Information

We are given that the coach let the players decide whether they had to do weight lifting or exercise, and at last he will select by the push-ups, and we have to find out which principle of experiment is violated and how it could lead to confounding.

02

Explanation

There are three principles of experimental design: comparison, random assignment, and control and replication.

From these, comparison is satisfied because weight lifting and exercise are compared and control and replication are also satisfied because weight lifting is a control treatment.

However, random assignment is not satisfied because the coach lets the players decide the treatment and treatment is not given to them randomly. This could lead to confounding because the players' choosing weight lifting can be similar and that can affect the results.

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.

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

Boys don’t cry? Two female statistics students asked a random sample of 60 high school

boys if they have ever cried during a movie. Thirty of the boys were asked directly and the

other 30 were asked anonymously by means of a “secret ballot.” When the responses were

anonymous, 63% of the boys said “Yes,” whereas only 23% of the other group said “Yes.”

Explain why the two percentages are so different.

Miami's car colorsUsing a webcam, a traffic analyst selected a random sample of 800cars traveling on I-195in Miami on a weekday morning. Among the 800cars in the sample, 24%were white. The margin of error for this estimate is 3.0percentage points.

a. Would you be surprised if a census revealed that 26%of cars onI-195 in Miami on a weekday morning were white? Explain your answer.

b. Explain how the traffic analyst could decrease the margin of error.

A local news agency conducted a survey about unemployment by randomly dialing phone

numbers during the work day until it gathered responses from 1000 adults in its state. In

the survey, 19% of those who responded said they were not currently employed. In reality,

only 6% of the adults in the state were not currently employed at the time of the survey.

Which of the following best explains the difference in the two percentages?

a. The difference is due to sampling variability. We shouldn’t expect the results of a

random sample to match the truth about the population every time.

b. The difference is due to response bias. Adults who are employed are likely to lie and

say that they are unemployed.

c. The difference is due to undercoverage bias. The survey included only adults and did

not include teenagers who are eligible to work.

d. The difference is due to nonresponse bias. Adults who are employed are less likely to

be available for the sample than adults who are unemployed.

e. The difference is due to voluntary response. Adults are able to volunteer as a member

of the sample.

Foster care versus orphanages Do abandoned children placed in foster homes do better than similar children placed in an institution? The Bucharest Early Intervention Project found statistically significant evidence that they do. The subjects were 136young children abandoned at birth and living in orphanages in Bucharest, Romania. Half of the children, chosen at random, were placed in foster homes. The other half remained in the orphanages. (Foster care was not easily available in Romania at the time and so was paid for by the study.) What conclusion can we draw from this study? Explain your reasoning.

Checking for bias Comment on each of the following as a potential sample survey

question. Is the question clear? Is it slanted toward a desired response?

a. Which of the following best represents your opinion on gun control?

i. The government should confiscate our guns.

ii. We have the right to keep and bear arms.

b. A freeze in nuclear weapons should be favored because it would begin a much-needed

process to stop everyone in the world from building nuclear weapons now and reduce

the possibility of nuclear war in the future. Do you agree or disagree?

See all solutions

Recommended explanations on Math Textbooks

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