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Ch. 10 - Correlation and Regression
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446당신이 사용하는 게 아니라요?교과서 변경
10장, 문제 10.3.3

Coefficient of Determination Using the heights and weights described in Exercise 1, the linear correlation coefficient r is 0.394. Find the value of the coefficient of determination. What practical information does the coefficient of determination provide?

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1
The coefficient of determination, denoted as R², is calculated by squaring the linear correlation coefficient r. The formula is: R2 = r2.
Substitute the given value of r (0.394) into the formula: R2 = 0.3942.
Simplify the expression by squaring 0.394 to find the value of R².
The coefficient of determination, R², represents the proportion of the variance in the dependent variable (e.g., weight) that is predictable from the independent variable (e.g., height).
In practical terms, the value of R² indicates how well the linear regression model explains the variability of the dependent variable. A higher R² value means a better fit of the model to the data.

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주요 개념

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Coefficient of Determination (R²)

The coefficient of determination, denoted as R², quantifies the proportion of variance in the dependent variable that can be explained by the independent variable(s) in a regression model. It ranges from 0 to 1, where 0 indicates no explanatory power and 1 indicates perfect explanation. In practical terms, a higher R² value suggests a better fit of the model to the data.
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Correlation Coefficient

Linear Correlation Coefficient (r)

The linear correlation coefficient, represented as r, measures the strength and direction of a linear relationship between two variables. Its value ranges from -1 to 1, where values close to 1 indicate a strong positive correlation, values close to -1 indicate a strong negative correlation, and values around 0 suggest no linear correlation. The square of r (r²) is used to calculate the coefficient of determination.
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Correlation Coefficient

Practical Interpretation of R²

The practical interpretation of the coefficient of determination (R²) provides insights into how well the independent variable(s) predict the dependent variable. For instance, if R² is 0.155, it indicates that approximately 15.5% of the variance in the dependent variable can be explained by the independent variable. This information is crucial for assessing the effectiveness of the model in real-world applications.
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Finding the Best Model

In Exercises 5–16, construct a scatterplot and identify the mathematical model that best fits the given data. Assume that the model is to be used only for the scope of the given data, and consider only linear, quadratic, logarithmic, exponential, and power models.

Richter Scale The table lists different amounts (metric tons) of the explosive TNT and the corresponding value measured on the Richter scale resulting from explosions of the TNT.

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Correlation and Slope What is the relationship between the linear correlation coefficient r and the slope b1 of a regression line?

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Regression and Predictions

Exercises 13–28 use the same data sets as Exercises 13–28 in Section 10-1.


Find the regression equation, letting the first variable be the predictor (x) variable.

Find the indicated predicted value by following the prediction procedure summarized in Figure 10-5.

Subway and the CPI Use the subway/CPI data from the preceding exercise. What is the best predicted value of the CPI when the subway fare is \$3.00?

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Finding the Best Model

In Exercises 5–16, construct a scatterplot and identify the mathematical model that best fits the given data. Assume that the model is to be used only for the scope of the given data, and consider only linear, quadratic, logarithmic, exponential, and power models.

Sound Intensity The table lists intensities of sounds as multiples of a basic reference sound. A scale similar to the decibel scale is used to measure the sound intensity.

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Randomization

For Exercises 33–36, repeat the indicated exercise using the resampling method of randomization.

Powerball Jackpots and Tickets Sold Exercise 14

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Standard Error of Estimate A random sample of 118 different female statistics students is obtained and their weights are measured in kilograms and in pounds. Using the 118 paired weights (weight in kg, weight in lb), what is the value of se? For a female statistics student who weighs 100 lb, the predicted weight in kilograms is 45.4 kg. What is the 95% prediction interval?

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