Math Problem Statement

Twenty different statistics students are randomly selected. For each of​ them, their body temperature

​(degrees°​C)

is measured and their head circumference​ (cm) is measured. If it is found that

requals=​0,

does that indicate that there is no association between these two​ variables?

Question content area bottom

Part 1

Choose the correct answer below.

A.

​No, because if

requals=​0,

the variables are in a perfect linear relationship.

B.

​No, because r does not measure the strength of the​ relationship, only its direction.

C.

​No, because while there is no linear​ correlation, there may be a relationship that is not linear.

D.

​Yes, because if

requals=​0,

the variables are completely unrelated.

Solution

The correct answer is:

C. No, because while there is no linear correlation, there may be a relationship that is not linear.

Explanation:

  1. The correlation coefficient rr measures the strength and direction of a linear relationship between two variables.
  2. If r=0r = 0, it indicates no linear correlation, meaning the data does not follow a linear pattern.
  3. However, r=0r = 0 does not rule out the possibility of a non-linear relationship. For example, there might be a curved or complex pattern that a linear correlation cannot detect.

Why other options are incorrect:

  • A is incorrect because r=0r = 0 indicates no linear relationship, not a perfect linear relationship.
  • B is incorrect because rr measures both the strength and direction of a linear relationship.
  • D is incorrect because r=0r = 0 does not imply that the variables are completely unrelated; it only suggests they are not linearly related.

Would you like a deeper dive into this topic or have any follow-up questions?

5 Follow-Up Questions:

  1. What is the range of values for the correlation coefficient rr?
  2. How can you detect non-linear relationships between two variables?
  3. What methods besides correlation can be used to identify relationships between variables?
  4. What does a correlation coefficient of r=1r = 1 or r=1r = -1 indicate?
  5. Can the correlation coefficient be used for categorical data?

Tip:

When analyzing data, always look at a scatterplot first; it helps in visualizing both linear and non-linear relationships.

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Math Problem Analysis

Mathematical Concepts

Statistics
Correlation
Linear vs. Non-Linear Relationships

Formulas

Correlation Coefficient r

Theorems

Properties of Correlation Coefficient

Suitable Grade Level

Grades 11-12