Question 1

Which of the following best describes the relationship shown in the scatterplot between the percentage of graduates taking the SAT and the state mean SAT Mathematics score?

Accepted Answer

There is a strong negative linear association.

Question 2

In a scatterplot, what does an outlier represent?

Accepted Answer

A value that falls outside the overall pattern of the relationship.

Question 3

If the correlation coefficient $$r$$ between two variables is close to 0, what does the scatterplot most likely show?

Accepted Answer

A cloud of points with no visible pattern.

Question 4

Researchers found a correlation of $$r = 0.3$$ between soda consumption (in ounces) and aggression rating. If soda consumption was measured in litres instead of ounces (1 litre = 35 ounces), what would the correlation be?

Accepted Answer

$$0.3$$

Question 5

Which variable is typically placed on the horizontal axis in a scatterplot?

Accepted Answer

The explanatory variable.

Question 6

A scatterplot of boats registered in Florida (thousands) versus Florida manatees killed by boats shows a strong positive association. Which of the following best describes this relationship?

Accepted Answer

As the number of boats increases, the number of manatees killed increases.

Question 7

Given the formula for the Pearson correlation coefficient:

$$ r = \frac{1}{n-1} \sum \left( \frac{x_i - \bar{x}}{s_x} \right) \left( \frac{y_i - \bar{y}}{s_y} \right) $$

What does $$r$$ measure?

Accepted Answer

The strength and direction of a linear relationship between two quantitative variables.

Question 8

In the coral reef study, sea surface temperature is the explanatory variable and coral growth is the response variable. If the correlation $$r is $$negative, what does this indicate?

Accepted Answer

Higher sea surface temperatures are associated with lower coral growth.

Question 9

Which of the following is NOT a fact about correlation?

Accepted Answer

Correlation can be used to describe nonlinear relationships.

Question 10

A scatterplot is made for Midwest and Northeast states, using different colors for each region. What is the purpose of adding categorical variables to a scatterplot?

Accepted Answer

To distinguish groups within the data and reveal patterns specific to each category.

Question 11

If a scatterplot shows a negative linear pattern and the calculated correlation is $$r = -0.81$$, what can you conclude?

Accepted Answer

There is a strong negative linear relationship.

Question 12

Which of the following best describes a positive association between two variables?

Accepted Answer

Above-average values of one variable tend to accompany above-average values of the other.

Question 13

Suppose you have a scatterplot with a strong linear pattern but one point is far from the rest. What is this point called?

Accepted Answer

An outlier.

Question 14

Which step in the four-step process for making a scatterplot involves examining the plot for relationships and patterns?

Accepted Answer

SOLVE

Question 15

If the correlation coefficient $$r is $$calculated as $$-0.808$$ for a dataset, what does this value indicate about the relationship between the variables?

Accepted Answer

There is a strong negative linear relationship.

Question 16

Which of the following is a correct interpretation of a scatterplot showing a cloud of points with no visible pattern?

Accepted Answer

The correlation is close to 0.

Question 17

A researcher wants to investigate how sea surface temperature affects coral growth. Which variable should be considered the explanatory variable?

Accepted Answer

Sea surface temperature.

Question 18

Which of the following statements about the Pearson correlation coefficient $$r is $$true?

Accepted Answer

$$r is $$affected by outliers.

Question 19

If you add a categorical variable to a scatterplot, what is the best way to visually represent it?

Accepted Answer

Use a different plot color or symbol for each category.

Question 20

Which of the following is NOT a step in the four-step process for making a scatterplot?

Accepted Answer

ANALYZE

Microeconomics Study Guide: Scatterplots and Correlation

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