Math Problem Statement

An Economics instructor assigns a class to investigate factors associated with the gross domestic product (GDP) of nations. Each student examines a different factor (such as life expectancy, literacy rate, etc.) for a few countries and reports to the class. Apparently, some of the classmates do not understand Statistics very well because several of their conclusions are incorrect. Explain the mistakes in comments a and b below.

Solution

For the questions in the image:

Part a:

The correlation coefficient of -0.772 does not indicate "a very low correlation" as stated. In fact, this value shows a strong negative linear relationship between GDP and the infant mortality rate.

Correct Answer:

D. Assuming the relation is linear, a correlation of -0.772 shows a strong relation in a negative direction.

Part b:

The correlation mentioned (0.44 between GDP and Continent) is incorrect because continent is a categorical variable, and correlation does not apply to such variables. Correlation is used to measure the linear relationship between two quantitative variables.

Correct Answer:

C. Continent is a categorical variable. Correlation does not apply.

Let me know if you'd like a detailed explanation of correlation concepts or the reasoning for these answers.

Related Questions:

  1. What does the strength of a correlation coefficient signify?
  2. How can you interpret a positive vs. negative correlation?
  3. Why can't correlation be applied to categorical variables like continents?
  4. What are examples of weak vs. strong correlation coefficients?
  5. How can outliers affect the interpretation of correlation?

Tip:

Correlation values range from -1 to +1. Values closer to ±1 indicate stronger relationships, while values near 0 indicate weaker or no relationships.

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Math Problem Analysis

Mathematical Concepts

Correlation
Linear relationships
Quantitative and categorical variables

Formulas

Correlation coefficient formula

Theorems

Properties of the correlation coefficient
Applicability of correlation to quantitative variables

Suitable Grade Level

College level