Quiz #2 - Chapter 2 - Summarizing Distributions

Question 1

In a frequency distribution, which quantity describes the number of respondents providing a particular response?

A: Cumulative percent (cumulative %)
B: Count (Frequency)
C: Percent (% of total)

Answer 1

B: Count (Frequency)

Question 2

A study explored the effectiveness of a new mindfulness intervention in terms of stress reduction. They found that the distribution of stress levels of all participants in the study is left-skewed. What does this distribution of stress levels look like?

A: There are even numbers of participants for each level of stress.

B: More participants are under high levels of stress and less participants are under low levels of stress.

C: More participants are under low levels of stress and less participants are under high levels of stress.

Answer 2

B: More participants are under high levels of stress and less participants are under low levels of stress.

Question 3

A dog food company tests whether dogs like a new flavor of dog food. They measure how many ounces of food each dog eats. If they want to display the distribution of the ounces eaten by 100 dogs in a figure, which figure(s) should they use? Select all that apply.

A: Histogram
B: Frequency distribution table
C: Density plot
D: Bar plot

Answer 3

A: Histogram AND C: Density plot

• Histograms pair with density plots and are used for numerical data (ratio and interval).
• Bar plots pair with frequency distribution tables and are used for categorical data (nominal and ordinal).
• When choosing an answer for a question like this make sure to pay attention to whether a variable is categorical or numerical not by checking whether your participants (dogs) are categorical or numerical but whether the RESPONSES (ounces of food) are categorical or numerical. The RESPONSES in this example is to number of ounces of food, which is a numeric variable. Hence, we cannot use bar plots.

Question 4

A researcher for an ice cream company has a sample of customers taste three flavors of ice cream: vanilla, chocolate, and strawberry. After they taste the flavors, the researcher asks each customer which flavor was their favorite, and then she records the flavor each person said they liked the most. If the researcher wants to display the distribution of the customers’ responses in a figure, what should she use? Select all that apply.

A: Frequency distribution table
B: Bar plot
C: Histogram
D: Density plot

Answer 4

A: Frequency distribution table AND B: Bar plot

• Histograms pair with density plots and are used for numerical data (ratio and interval).
• Bar plots pair with frequency distribution tables and are used for categorical data (nominal and ordinal).
• When choosing an answer for a question like this make sure to pay attention to whether a variable is categorical or numerical not by checking whether your participants (customers) are categorical or numerical but whether the RESPONSES (favorite ice cream flavor) are categorical or numerical. The RESPONSES in this example are favorite ice cream flavor, which is a categorical variable. Hence, we cannot use a histogram.

Question 5

If a distribution is flatter than a normal distribution, the kurtosis is:

A: We don’t know
B: zero
C: negative
D: positive

Answer 5

C: negative

Question 6

If a distribution is negatively skewed, the kurtosis is:

A: positive
B: negative
C: We don’t know
D: zero

Answer 6

C: We don’t know

Question 7

If a distribution is negatively skewed, the skewness is:

A: positive
B: negative
C: zero
D: We don’t know

Answer 7

B: negative

Question 8

The higher the density, the:

A: more often/likely it is to observe some value
B: less often/likely it is to observe some value
C: higher the kurtosis
D: lower the kurtosis

Answer 8

A: more often/likely it is to observe some value

Question 9

Which of the following are symmetric distributions? Select all that apply.

A: Normal Distributions
B: Left-skewed distributions
C: Right-skewed distributions
D: Distributions with kurtosis of 0
E: Uniform Distributions

Answer 9

A: Normal Distributions AND E: Uniform Distributions

• A normal distribution has a kurtosis of 0, but it’s important to note that not all distributions with a kurtosis of 0 are normal distributions so it cannot be an answer to this particular question!

Question 10

When a distribution has skewness above 2, which of the following is true?

A: It also has a kurtosis above 2
B: It is left-skewed
C: It is right-skewed
D: It is negatively skewed

Answer 10

C: It is right-skewed

Question 11

A study of post-partum depression found a relatively even number of mothers with low, moderate, and high depression levels. What distribution shape best describes the depression variable?

A: Positively skewed
B: Normal
C: Negatively skewed
D: Uniform

Answer 11

D: Uniform

Question 12

NOTE: Please see additional notes in Google Docs for this quiz. There were several questions that required images which I cannot use here. Study those questions too!!!

Answer 12

See Google Docs for more questions and answers!!!