Chapter 1. Cautions about Experimentation

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Question 1

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Question 1.1

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Correct. Factors that the researcher cannot control such as bad weather, drop outs, death of animals, etc., can create problems in experiments.
Incorrect. Factors that the researcher cannot control such as bad weather, drop outs, death of animals, etc., can create problems in experiments.
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Questions 2-3

1:37

Question 1.2

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Correct. Treating all cows the same will remove the hidden bias. Further, all cows need ear tags so that all cows are treated the same. Spraying with insecticide will just add another bias.
Incorrect. Treating all cows the same will remove the hidden bias. Further, all cows need ear tags so that all cows are treated the same. Spraying with insecticide will just add another bias.
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Question 1.3

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Correct. The explanatory variable, insecticide ear tag versus placebo ear tag, is confounded with the lurking variable, fenced-in or not.
Incorrect. The explanatory variable, insecticide ear tag versus placebo ear tag, is confounded with the lurking variable, fenced-in or not.
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Questions 4-5

2:23

Question 1.4

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Correct. Doctors diagnosing the response may be influenced by knowing which subject receives the placebo and which subject received the active treatment. This may bias their diagnosis.
Incorrect. Doctors diagnosing the response may be influenced by knowing which subject receives the placebo and which subject received the active treatment. This may bias their diagnosis.
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Question 1.5

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Correct. If subjects in an active treatment group received a “pill” and subjects in the control group did not, the subjects in the active treatment group may respond to the “pill” and not to the treatment. This results in a placebo effect.
Incorrect. If subjects in an active treatment group received a “pill” and subjects in the control group did not, the subjects in the active treatment group may respond to the “pill” and not to the treatment. This results in a placebo effect.
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Question 6

3:02

Question 1.6

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Correct. Both the researcher and the statistician need to know which treatment each subject receives, but the doctor or nurse may be biased by knowing which treatment each subject receives.
Incorrect. Both the researcher and the statistician need to know which treatment each subject receives, but the doctor or nurse may be biased by knowing which treatment each subject receives.
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Questions 7-8

4:17

Question 1.7

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Correct. All of these may result in lack of realism.
Incorrect. All of these may result in lack of realism.
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Question 1.8

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Correct. Lack of realism results in bias.
Incorrect. Lack of realism results in bias.
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Questions 9-10

4:48

Question 1.9

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Correct. Due to ethical reasons, realism may not be possible.
Incorrect. Due to ethical reasons, realism may not be possible.
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Question 1.10

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Correct. Due to ethical reasons, realism may not be possible. For example, making pregnant women take drugs to study the effect of these drugs on fetuses will never be allowed and yet this information is important. So, using common sense is the best alternative.
Incorrect. Due to ethical reasons, realism may not be possible. For example, making pregnant women take drugs to study the effect of these drugs on fetuses will never be allowed and yet this information is important. So, using common sense is the best alternative.
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