Chapter 8 Quiz Review

The ____ hypothesis states that in the general population, there is no change, no difference, or no relationship.

• H_o (Null)

• H₁ (Alternative)

The ___ hypothesis states that there is a change, a difference, or a relationship for the general population.

• H_o (Null)

• H₁ (Alternative)

A researcher is investigating the effectiveness of a new medication that is intended to lower cholesterol. What would the null hypothesis be in words?

• H₀ : The medication has no effect

• H₀ : The medication has an effect

• H₀ : The cholesterol levels are lower

• H₀ : The cholesterol levels are higher

If the alpha level is increased from α = .01 to α = .05, the size of the critical region also increases.

• True

• False

Answer explanation

True. A larger alpha level means that the boundaries for the critical region move closer to the center of the distribution, making you more likely to have a significant effect.

A decision to reject the null hypothesis means you have demonstrated that the treatment has no effect.

• True

• False

Answer explanation

False. Rejecting the null hypothesis means you have concluded that the treatment does have an effect.

The ____ ______ is composed of extreme sample values that are very unlikely to be obtained if the null hypothesis is true. 

• Alpha Level

• Null Hypothesis

• Critical Region

• Hypothesis Testing

A discrepancy from the sample statistics to the population parameter is known as ____ _____.

• Inferential statistics

• Alpha Level

• Alternative Hypothesis

• Sampling Error

If a researcher conducted a hypothesis test with an alpha level of α = 0.04, what z-score values would form the boundaries for the critical region?

• z = (+/-) 1.75

• z = (+/-) 2.05

• z = (+/-) 1.96

• z = (+/-) 2.80

Answer explanation

First, we must split our alpha in half since this is a two-tailed test: α = 0.04/2 = 0.02. Now, we must look in the Tail (C) column of the unit normal table to see what z-score is closest to matching 0.02. We should get z = (+/-) 2.05 since it is equivalent to a proportion of p = 0.0202.

When you reject the null hypothesis that is really true, you have made a ____ error.

• Sampling

• Type II

• Type I

• Statistical

Answer explanation

A type I error is when we claim the treatment had an effect, when it really didn't.

A researcher predicts that their treatment will increase scores. If this researcher uses an alpha level of α = .01, what z-score will define the critical region?

• z = 2.33

• z = 1.96

• z = -2.33

• z = -1.96

Answer explanation

After reading the problem, we can see that this is a one-tailed test since there is a suggested direction: increase. In order to determine the z-score that forms the critical region, we must look in the tail (C) column to find the proportion closest to 0.01, then see what z-score that aligns with. We should get z = 2.33 since the proportion in the tail is p = 0.0099