Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 4: Q 1.1. (page 233)

Does reducing screen brightness increase battery life in laptop computers? To find out, researchers obtained 30new laptops of the same brand. They chose 15of the computers at random and adjusted their screens to the brightest setting. The other 15laptop screens were left at the default setting—moderate brightness. Researchers then measured how long each machine’s battery lasted.

Was this an observational study or an experiment? Justify your answer.

Short Answer

Expert verified

Experimental Study.

Step by step solution

01

Given information

They randomly selected 15 laptops and set their screens to the brightest setting. The default setting for the other 15 laptop screens was moderate brightness.

02

Concept

Observational research looks at people and assesses factors of interest without trying to affect their responses.

Individuals are purposely subjected to a treatment in order to measure their responses in an experiment.

03

Explanation

This is an experimental study in which the evaluation group and the control group are both classes, each with the appropriate variable adjustments to meet the criteria in a controlled setting.

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

A survey paid for by makers of disposable diapers found that 84% of the sample opposed banning disposable diapers. Here is the actual question:

It is estimated that disposable diapers account for less than 2%of the trash in today’s landfills. In contrast, beverage containers, third-class mail, and yard wastes are estimated to account for about 21% of the trash in landfills. Given this, in your opinion, would it be fair to ban disposable diapers? Explain how the wording of the question could result in bias. Be sure to specify the direction of the bias.

What kind of error? Which of the following are sources of sampling error and which are sources of non-sampling error? Explain your answers.

(a) The subject lies about past drug use.

(b) A typing error is made in recording the data.

(c) Data are gathered by asking people to mail in a coupon printed in a newspaper.

Sampling gravestones The local genealogical society in Coles County, Illinois, has compiled records on all 55,914 gravestones in cemeteries in the county from the years 1825 to 1985 Historians plan to use these records to learn about African Americans in Coles County’s history. They first choose an SRS of 395 records to check their accuracy by visiting the actual gravestones.13

(a) Explain how you would use technology or Table D to choose the SRS. Your description should be clear enough for a classmate to obtain your results.

(b) Use your method from (a) to choose the first 3 gravestones.

Prayer and meditation You read in a magazine that “nonphysical treatments such as meditation and prayer have been shown to be effective in controlled scientific studies for such ailments as high blood pressure, insomnia, ulcers, and asthma.” Explain in simple language what the article means by “controlled scientific studies.” Why can such studies provide good evidence that meditation is an effective

treatment for high blood pressure?

Meditation for anxiety An experiment that claimed to show that meditation lowers anxiety proceeded as follows. The experimenter interviewed the subjects and rated their level of anxiety. Then the subjects were randomly assigned to two groups. The experimenter taught one group how to meditate and they meditated daily for a month. The other group was simply told to relax more. At the end of the month, the experimenter interviewed all the subjects again and rated their anxiety level. The meditation group now had less anxiety. Psychologists said that the results were suspect because the ratings were not blind. Explain what this means and how lack of blindness could bias the reported results.
See all solutions

Recommended explanations on Math Textbooks

Logic and Functions

Read Explanation

Probability and Statistics

Read Explanation

Decision Maths

Read Explanation

Mechanics Maths

Read Explanation

Theoretical and Mathematical Physics

Read Explanation

Statistics

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