In 2013, psychology researchers conducted an experiment featuring 40 undergraduate college students, each of whom took a 20-question general-knowledge test on a computer. Participants were given four possible answers and instructed to pick the correct one. Before doing so, half the students were told that just before each question was asked, the correct answer was momentarily flashed onto the screen. They were informed that this happened too quickly for them to process the information consciously, but assured that it would register in their brains. This was the placebo treatment. In the control treatment participants were not told this. The researchers write that: “Participants in the placebo condition who believed they had been exposed to the correct answers subliminally scored higher than participants in the control condition.” The researchers conducted a hypothesis test to determine if the proportion of correct answers is significantly different for participants in the placebo condition and participants in the control condition (placebo proportion minus control proportion). The P-value is 0.02. What can the researchers conclude? Researchers reject the null hypothesis. The proportion of correct answers for participants in the placebo condition is no different than the proportion of correct answers for participants in the control group. Researchers fail to reject the null hypothesis. The proportion of correct answers is different, but not significantly different. Researchers reject the null hypothesis. The proportion of correct answers is significantly different for the placebo condition and the control group. Researchers reject the null hypothesis. The proportion of correct answers for participants in the placebo condition is significantly higher than the proportion of correct answers for participants in the control group.

Holt Mcdougal Larson Pre-algebra: Student Edition 2012

1st Edition

ISBN:9780547587776

Author:HOLT MCDOUGAL

Publisher:HOLT MCDOUGAL

Chapter11: Data Analysis And Probability

Section: Chapter Questions

Problem 8CR

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In 2013, psychology researchers conducted an experiment featuring 40 undergraduate college students, each of whom took a 20-question general-knowledge test on a computer. Participants were given four possible answers and instructed to pick the correct one. Before doing so, half the students were told that just before each question was asked, the correct answer was momentarily flashed onto the screen. They were informed that this happened too quickly for them to process the information consciously, but assured that it would register in their brains. This was the placebo treatment. In the control treatment participants were not told this.

The researchers write that: “Participants in the placebo condition who believed they had been exposed to the correct answers subliminally scored higher than participants in the control condition.”

The researchers conducted a hypothesis test to determine if the proportion of correct answers is significantly different for participants in the placebo condition and participants in the control condition (placebo proportion minus control proportion). The P-value is 0.02. What can the researchers conclude?

Researchers reject the null hypothesis. The proportion of correct answers for participants in the placebo condition is no different than the proportion of correct answers for participants in the control group.

Researchers fail to reject the null hypothesis. The proportion of correct answers is different, but not significantly different.

Researchers reject the null hypothesis. The proportion of correct answers is significantly different for the placebo condition and the control group.

Researchers reject the null hypothesis. The proportion of correct answers for participants in the placebo condition is significantly higher than the proportion of correct answers for participants in the control group.

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