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Chapter 4: Q 52. (page 253)

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.

Short Answer

Expert verified

Subjects: The students in the dormitory picked.

Explanatory variable: composition of prices.

Treatments: one flat rate payable or one on / off peak rate payable.

Variables of response: quantity, time and overall network utilization.

Step by step solution

01

Given information  

The experimental units, explanatory and response variables, and treatments must all be identified.

02

Concept

The treatments are randomly assigned to all of the experimental units in a completely randomized design.

In a double-blind experiment, neither the subjects nor the persons who interact with them and evaluate their responses are aware of the therapy they received.

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

A specific disorder is referred to as a treatment for participants in a study.

The students in the dorm choose the subjects.

Price composition is an explanatory variable.

Treatments include a single flat cost or an on/off-peak rate.

Quantity, time, and total network use are the response variables.

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Most popular questions from this chapter

Random digits Which of the following statements are true of a table of random digits, and which are false? Briefly explain your answers.

(a) There are exactly four 0s in each row of 40 digits.

(b) Each pair of digits has a chance 1/100 of being 00

(c) The digits 0000 can never appear as a group

because this pattern is not random.

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.

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Chocolate gets my heart pumping Cardiologists at Athens Medical School in Greece wanted to test whether chocolate affected blood flow in the blood vessels. The researchers recruited 17healthy young volunteers, who were each given a 3.5-ounce bar of dark chocolate, either bittersweet or fake chocolate.

On another day, the volunteers were switched. The subjects had no chocolate outside the study, and investigators didn鈥檛 know whether a subject had eaten the real or the fake chocolate. An ultrasound was taken of each volunteer鈥檚 upper arm to see the functioning of the cells in the walls of the main artery. The investigators found that blood vessel function was improved when the subjects ate bittersweet chocolate, and that there were no such changes when they ate the placebo (fake chocolate).

(a) What type of design did the investigators use in their study?

(b) Explain why the investigators chose this design instead of a completely randomized design.

(c) Why is it important to randomly assign the order of the treatments for the subjects?

In an interesting experiment, researchers examined the effect of ultrasound on birth weight. Pregnant women participating in the study were randomly assigned to one of two groups. The first group of women received an ultrasound; the second group did not. When the subjects鈥� babies were born, their birth weights were recorded. The women who received the ultrasounds had heavier babies.

Did the experimental design take the placebo effect into account? Why is this important?
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