DA0-002 Data Analysis Practice Question
A simple linear regression model predicts sales (y) from advertising spend (x). The equation is y = 2.5x + 10, and R² = 0.81. Which interpretation is correct?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
81% of the variation in sales is explained by advertising spend.
Slope indicates that each unit increase in x increases y by 2.5 units. R² of 0.81 means 81% of variance in y is explained by x.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The correlation between sales and advertising is 0.81.
Why it's wrong here
R² = r², so r = sqrt(0.81)=0.9.
- ✗
When advertising is $0, sales are $2.5.
Why it's wrong here
Intercept is 10, so when x=0, y=10.
- ✓
81% of the variation in sales is explained by advertising spend.
Why this is correct
R² = 0.81 means 81% explained.
- ✗
For every $1 increase in advertising, sales increase by $10 on average.
Why it's wrong here
Slope is 2.5, not 10.
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