/*! 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. 4.5 The National Halothane Study was... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 4: Q. 4.5 (page 288)

The National Halothane Study was a major investigation of the safety of anesthetics used in surgery. Records of over 850,000operations performed in 34major hospitals showed the following death rates for four common anesthetics :


There seems to be a clear association between the anesthetic used and the death rate of patients. Anesthetic C appears to be more dangerous.

a. Explain why we call the National Halothane Study an observational study rather than an experiment, even though it compared the results of using different anesthetics in actual surgery.

b. Identify the explanatory and response variables in this study.

c. When the study looked at other variables that are related to a doctor鈥檚 choice of anesthetic, it found that Anesthetic C was not causing extra deaths. Explain the concept of confounding in this context and identify a variable that might be confounded with the doctor鈥檚 choice of anesthetic.

Short Answer

Expert verified

a. We call the National Halothane Study an observational study rather than an experiment because an observational study tries to gather information without disturbing the scene.

b. The explanatory is the type of anesthetic and the response variable is the death rate in this study.

c. The concept of confounding in this context and identifying a variable that might be confounded with the doctor鈥檚 choice of anesthetic is one possible confounding variable is a type of surgery. If one anesthesia is used more often with a type of surgery has a higher death rate anyway. We wouldn't know if the death rate was higher because of the anesthesia type or the surgery type.

Step by step solution

01

Part (a) step 1: Given Information

We need to explain whether we call the National Halothane Study an observational study rather than an experiment, even though it compared the results of using different anesthetics in actual surgery.

02

Part (a) step 2: Explanation

Here,

The experiment deliberately imposes some treatment on individuals in order to observe the responses.

An observational study tries to gather information without disturbing the scene they are observing.

So records are used, no treatment was deliberately imposed on individuals and thus the study is an observational study.

03

Part (b) step 1: Given Information

We need to identify the explanatory and response variables in this study.

04

Part (b) step 2: Explanation

A response variable is a variable that measures an outcome or result of a study, while an explanatory variable is a variable that we think explains or causes changes in the response variables.

We expect a different anesthetic to affect the death rate, which implies that the explanatory variable is a type of anesthetic and the response variable is the death rate.

05

Part (c) step 1: Given Information

We need to explain the concept of confounding in this context and identify a variable that might be confounded with the doctor鈥檚 choice of anesthetic.

06

Part (c) step 2: Explanation

Variables are confounded when the effects on a response variable can't be distinguished.

One possible confounding variable is the type of surgery. If one anesthesia is used often with a type of surgery that has a higher death rate anyway, we wouldn't know if the death rate was higher because of the anesthesia type or the surgery type.

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

Consider an experiment to investigate the effectiveness of different insecticides in

controlling pests and their impact on the productivity of tomato plants. What is the best

reason for randomly assigning treatment levels (spraying or not spraying) to the

experimental units (farms)?

a. Random assignment eliminates the effects of other variables, like soil fertility.

b. Random assignment eliminates chance variation in the responses.

c. Random assignment allows researchers to generalize conclusions about the

effectiveness of the insecticides to all farms.

d. Random assignment will tend to average out all other uncontrolled factors such as

soil fertility so that they are not confounded with the treatment effects.

e. Random assignment helps avoid bias due to the placebo effect.

A study of treatments for angina (pain due to low blood supply to the heart) compared

bypass surgery, angioplasty, and use of drugs. The study looked at the medical records

of thousands of angina patients whose doctors had chosen one of these treatments. It

found that the average survival time of patients given drugs was the highest. What do

you conclude?

a. This study proves that drugs prolong life and should be the treatment of choice.

b. We can conclude that drugs prolong life because the study was a comparative

experiment.

c. We can鈥檛 conclude that drugs prolong life because the patients were volunteers.

d. We can鈥檛 conclude that drugs prolong life because the groups might differ in ways

besides the treatment.

e. We can鈥檛 conclude that drugs prolong life because no placebo was used.

A gardener wants to try different combinations of fertilizer (none, 1cup, 2cups) and mulch (none, wood chips, pine needles, plastic) to determine which combination produces the highest yield for a variety of green beans. He has 60green-bean plants to use in the experiment. If he wants an equal number of plants to be assigned to each treatment, how many plants will be assigned to each treatment?

a. 1

b. 3

c. 4

d. 5

e.12

High-speed Internet Laying fiber-optic cable is expensive. Cable companies want to make sure that if they extend their lines to less dense suburban or rural areas, there will be sufficient demand so the work will be cost-effective. They decide to conduct a survey to determine the proportion of households in a rural subdivision that would buy the service. They select a simple random sample of 5blocks in the subdivision and survey each family that lives on one of those blocks.

a. What is the name for this kind of sampling method?

b. Give a possible reason why the cable company chose this method.

More testosterone Refer to Exercise 56. Could blinding be used in this experiment? Explain your reasoning. Why is blinding an important consideration in this context?

See all solutions

Recommended explanations on Math Textbooks

Applied Mathematics

Read Explanation

Geometry

Read Explanation

Discrete Mathematics

Read Explanation

Pure Maths

Read Explanation

Calculus

Read Explanation

Probability and 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.