Questions: Determine whether the association between the two variables is positive or negative.
The weight of a car (in pounds) and its fuel efficiency (in miles per gallon)
Transcript text: Determine whether the association between the two variables is positive or negative.
The weight of a car (in pounds) and its fuel efficiency (in miles per gallon)
Solution
Solution Steps
Step 1: Collect Data
Data has been collected with weights of cars (in pounds) and their fuel efficiency (in miles per gallon).
Step 2: Plot Data
A scatter plot is created with car weight on the x-axis and fuel efficiency on the y-axis to visually inspect the relationship.
Step 3: Calculate Correlation Coefficient (r)
The Pearson correlation coefficient (r) is calculated using the formula for Pearson's r. The calculated value of r is -0.99.
Step 4: Interpret the Correlation
Since r = -0.99 < 0, there is a negative association between the weight of a car and its fuel efficiency, which aligns with common expectations.
Step 5: Statistical Significance
The p-value of the correlation coefficient is 0. If the p-value is less than 0.05, the correlation is considered statistically significant, indicating that the observed association is not due to random chance.
Final Answer:
The correlation between car weight and fuel efficiency is statistically significant with r = -0.99 and p-value = 0.