1. **Stating the problem:** We want to understand what the sample correlation coefficient $r$ measures and determine which value indicates a stronger correlation between $r=0.918$ and $r=-0.932$.
2. **Definition and formula:** The sample correlation coefficient $r$ measures the strength and direction of a linear relationship between two variables $X$ and $Y$. It is calculated by the formula:
$$r = \frac{\sum (x_i - \bar{x})(y_i - \bar{y})}{\sqrt{\sum (x_i - \bar{x})^2 \sum (y_i - \bar{y})^2}}$$
where $x_i$ and $y_i$ are individual sample points, and $\bar{x}$ and $\bar{y}$ are the sample means.
3. **Interpretation:** The value of $r$ ranges from $-1$ to $1$.
- $r = 1$ means a perfect positive linear correlation.
- $r = -1$ means a perfect negative linear correlation.
- $r = 0$ means no linear correlation.
4. **Strength of correlation:** The strength depends on the absolute value $|r|$.
- The closer $|r|$ is to $1$, the stronger the linear relationship.
- The sign of $r$ indicates the direction (positive or negative).
5. **Comparing $r=0.918$ and $r=-0.932$:**
- $|0.918| = 0.918$
- $|-0.932| = 0.932$
Since $0.932 > 0.918$, the correlation with $r = -0.932$ is stronger.
6. **Conclusion:** The sample correlation coefficient $r$ measures the strength and direction of a linear relationship between two variables. Between $r=0.918$ and $r=-0.932$, the value $r=-0.932$ indicates a stronger correlation because its absolute value is larger, even though it is negative, meaning a strong negative linear relationship.
Correlation Coefficient C0740C
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