## Setting Up Hypotheses

This section discusses the logic behind hypothesis testing using concrete examples and explains how to set up null and alternative hypothesis. It explains what Type I and II errors are and how they can occur. Finally, it introduces one-tailed and two-tailed tests and explains which one you should use for testing purposes.

### One- and Two-Tailed Tests

#### Questions

Question 1 out of 4.

Select all that apply. Which is/are true of two-tailed tests?

• They are appropriate when it is not important to distinguish between no effect and an effect in either direction.
• They are more common than one-tailed tests.
• They compute two-tailed probabilities.
• They are more controversial than one-tailed tests.

Question 2 out of 4.

You are testing the difference between college freshmen and seniors on a math test. You think that the seniors will perform better, but you are still interested in knowing if the freshmen perform better. What is the null hypothesis?

• The mean of the seniors is less than or equal to the mean of the freshmen
• The mean of the seniors is greater than or equal to the mean of the freshmen
• The mean of the seniors is equal to the mean of the freshmen

Question 3 out of 4.

You think a coin is biased and will come up heads more often than it will come up tails. What is the probability that out of 22 flips, it will come up heads 16 or more times? (Write your answer out to at least three decimal places).

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Question 4 out of 4.

You think a coin is biased, and you are interested in finding out if it is. What is the probability that out of 30 flips, it will come up one side 8 or fewer times? (Write your answer out to at least three decimal places).

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