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Chapter 4: Q 1.3. (page 233)

Does eating dinner with their families improve students’ academic performance? According to an ABC News article, “Teenagers who eat with their families at least five times a week are more likely to get better grades in

school.”19 This finding was based on a sample survey conducted by

researchers at Columbia University.

What are the explanatory and response variables?

Short Answer

Expert verified

Explanatory Variables: Laptop device screen brightness

Response variable: Battery life of the computer

Step by step solution

01

Given information

Teenagers who eat with their family at least five times per week are more likely to excel academically.

02

Concept

A lurking variable is one that is not included in the study's explanatory or response variables but has the potential to influence the response variable.

03

Explanation 

Based on the information provided:

Variables to Explain: The brightness of a laptop's screen

Computer battery life is a response variable.

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Most popular questions from this chapter

Sampling by accountants Accountants often use stratified samples during audits to verify a company’s records of such things as accounts receivable. The

stratification is based on the dollar amount of the item and often includes 100% sampling of the largest items. One company reports 5000 accounts receivable. Of these, 100 are in amounts over \(50,000;500 are in amounts between \)1000and\(50,000; and the remaining 4400are in amounts under \)1000Using these groups as strata, you decide to verify all the largest accounts and to sample 5% of the midsize accounts and 1%of the small accounts. How would you label the two strata from which you will sample? Use Table D, starting at line 115 to select only the first3 accounts from each of these strata.

A simple random sample of 1200 adult Americans is selected, and each person is asked the following question: “In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance?” Only 39% of those responding answered “Yes.” This survey

(a) is reasonably accurate since it used a large simple random sample.

(b) needs to be larger since only about 24 people were drawn from each state.

(c) probably understates the percent of people who favor a system of national health insurance.

(d) is very inaccurate but neither understates nor overstates the percent of people who favor a system of national health insurance. Since simple random sampling was used, it is unbiased.

(e) probably overstates the percent of people who favor a system of national health insurance.

Internet telephone calls You can use Voice over Internet Protocol (VoIP) to make long-distance

telephone calls over the Internet. How will the cost affect the use of this service? A university plans an experiment to find out. It will offer the service to all 350 students in one of its dormitories. Some students will pay a low flat rate. Others will pay higher rates at peak periods and very low rates off-peak. The university is interested in the amount and time of use and inthe effect on the congestion of the network.

Sleepless nights How much sleep do high school students get on a typical school night? An interested student designed a survey to find out. To make data collection easier, the student surveyed the first 100 students to arrive at school on a particular morning. These students reported an average of 7.2 hours of sleep on the previous night.

(a) What type of sample did the student obtain?

(b) Explain why this sampling method is biased. Is 7.2 hours probably higher or lower than the true average amount of sleep last night for all students at the

school? Why?

Running red lights The sample described in Exercise 31produced a list of 5024licensed drivers. The investigators then chose an SRS of 880 of these drivers to answer questions about their driving habits. One question asked was: “Recalling the last ten traffic lights you drove through, how many of them were red when you entered the intersections?” Of the 880 respondents, 171admitted that at least one light had been red. A practical problem with this survey is that people may not give truthful answers. What is the likely direction of the bias: do you think more or fewer than 171 of the 880 respondents really ran a red light? Why?
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