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Chapter 4: Q 3.2. (page 244)

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’ babies were born, their birth weights were recorded. The women who received the ultrasounds had heavier babies.

Was the experiment double-blind? Why is this important?

Short Answer

Expert verified

No.

Step by step solution

01

Given information 

Pregnant women participating in the study were randomly assigned to one of two groups.

02

Concept

In a double-blind experiment, neither the subjects nor the people who interact with them and assess the response variable are aware of the treatment they received.

03

Explanation

It wasn't double-blind because neither the subjects nor the researchers knew who had completed the study. Physicians were aware of this. It is critical to eliminate any bias.

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Most popular questions from this chapter

An example of a non-sampling error that can reduce the accuracy of a sample survey is

(a) using voluntary response to choose the sample.

(b) using the telephone directory as the sampling frame.

(c) interviewing people at shopping malls to obtain a sample.

(d) variation due to chance in choosing a sample at random.

(e) inability to contact many members of the sample.

Archaeologists plan to examine a sample of 2-meter square plots near an ancient Greek city for artifacts visible in the ground. They choose separate random samples of plots from the floodplain, coast, foothills, and high hills. What kind of sample is this?

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(b) A convenience sample

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Each of the following is a source of error in a sample survey. Label each as sampling error or non sampling error, and explain your answers.

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