/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q 1.1. Does reducing screen brightness ... [FREE SOLUTION] | 91影视

91影视

Log out

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鈥攎oderate brightness. Researchers then measured how long each machine鈥檚 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.

Over 30 million students worldwide already upgrade their learning with 91影视!

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

The drug manufacturer Merck recently stopped testing a promising new drug to treat depression. It

turned out that in a randomized, double-blind trial, a dummy pill did almost as well as the new drug. The fact that many people respond to a dummy treatment is called

(a) confounding. (d) the placebo effect.

(b) nonresponse. (e) bias.

(c) comparison.

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鈥檚 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.

Ring-no-answer A common form of nonresponse in telephone surveys is 鈥渞ing-no-answer.鈥� That is, a call is made to an active number but no one answers. The Italian National Statistical Institute looked at nonresponse to a government survey of households in Italy during the periods January 1 to Easter and July 1 to August 31 All calls were made between7 and 10 p.m., but 21.4% gave 鈥渞ing-no-answer鈥� in one period versus 41.5% 鈥渞ing-no-answer鈥� in the other period15 Which period do you think had the higher rate of no answers? Why? Explain why a high rate of nonresponse makes sample results less reliable.

Child care and aggression A study of child care enrolled 1364infants and followed them through

their sixth year in school. Later, the researchers published an article in which they stated that 鈥渢he more time children spent in child care from birth to age four-and-a-half, the more adults tended to rate them, both at age four-and-a-half and at kindergarten, as less likely to get along with others, as more assertive, as disobedient, and as aggressive.鈥�

(a) Is this an observational study or an experiment? Justify your answer.

(b) What are the explanatory and response variables?

(c) Does this study show that child care causes children to be more aggressive? Explain.

The Community Intervention Trial for Smoking Cessation asked whether a community-wide advertising campaign would reduce smoking. The researchers located 11pairs of communities, each pair similar in location, size, economic status, and so on. One community in each pair participated in the advertising campaign and the other did not. This is

(a) an observational study.

(b) a matched pairs experiment.

(c) a completely randomized experiment.

(d) a randomized block design, but not matched pairs.

(e) a stratified random sample.
See all solutions

Recommended explanations on Math Textbooks

Discrete Mathematics

Read Explanation

Mechanics Maths

Read Explanation

Geometry

Read Explanation

Calculus

Read Explanation

Applied Mathematics

Read Explanation

Decision Maths

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.