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Chapter 4: Q. 90 (page 269)

Two essential features of all statistically designed experiments are

a. comparing several treatments; using the double-blind method.

b. comparing several treatments; using chance to assign subjects to treatments.

c. always having a placebo group; using the double-blind method.

d. using a block design; using chance to assign subjects to treatments.

e. using enough subjects; always having a control group.

Short Answer

Expert verified

The correct option is (e). using enough subjects; always having a control group.

Step by step solution

01

Given information

Two basic highlights of all statistically planned tests are

02

Explanation

Statistically planned tests have three fundamental highlights: replication, randomization, and control. Replication implies that we have to replicate the test with numerous subjects, and hence we have got to utilize sufficient subjects. Randomization implies that we get randomization by arbitrarily selecting our subjects or haphazardly doling out the subjects to treatment groups. Control means that we require a control group (which may be a fake treatment group, but a fake treatment group isn't continuously required, such as when managing with plants or animals). We at that point note that reply alternative (e) best fits the basic highlights because it alludes to replication and control.

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Most popular questions from this chapter

Precise offers People often use round prices as first offers in a negotiation. But would a more precise number suggest that the offer was more reasoned and informed? In an experiment, 238adults played the role of a person selling a used car. Each adult received one of three initial offers: \(2000, \)1865(a precise under-offer), and \(2135(a precise over-offer). After hearing the initial offer, each subject made a counter-offer. The difference in the initial offer and counter-offer was the largest in the group that received the \)2000 offer. Describe how the researchers could have randomly assigned the subjects to the treatments

a. using slips of paper.

b. using technology.

c. using Table D.

Your statistics class has 30students. You want to ask an SRS of 5students from your class whether they use a mobile device for the online quizzes. You label the students 01,02,...,30. You enter the table of random digits at this line: 1445926056314248037165103622532249061181

Your SRS contains the students labeled

a. 14,45,92,60,56

b. 14,31,03,10,22

c. 14,03,10,22,22

d.14,03,10,22,06

e.14,03,10,22,11

A louse-y situation A study published in the New England Journal of Medicine compared two medicines to treat head lice: an oral medication called ivermectin and a topical lotion containing malathion. Researchers studied 812 people in 376 households in seven areas around the world. Of the 185 households randomly assigned to ivermectin, 171 were free from head lice after 2 weeks, compared with only 151 of the 191 households randomly assigned to malathion.

a. Calculate the difference (Ivermectin – Malathion) in the proportion of households that were free from head lice in the two groups.

One hundred trials of a simulation were performed to see what differences in proportions would occur due only to chance variation in the random assignment, assuming that the type of medication doesn’t matter. The results are shown in the dotplot.

b. There is one dot at 0.09. Explain what this dot means in this context.

c. Use the results of the simulation to determine if the difference in proportions from part (a) is statistically significant. Explain your reasoning.

Miami's car colorsUsing a webcam, a traffic analyst selected a random sample of 800cars traveling on I-195in Miami on a weekday morning. Among the 800cars in the sample, 24%were white. The margin of error for this estimate is 3.0percentage points.

a. Would you be surprised if a census revealed that 26%of cars onI-195 in Miami on a weekday morning were white? Explain your answer.

b. Explain how the traffic analyst could decrease the margin of error.

Funding for fine arts The band director at a high school wants to estimate the percentage

of parents who support a decrease in the budget for fine arts. Because many parents attend

the school’s annual musical, the director surveys the first 30parents who arrive at the

show. Explain how bias in the sampling method could affect the estimate.
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