What is the formula for the Least Squares Regression Line?
ŷ = a + bx, where ŷ = predicted y, x = explanatory variable, a = y-intercept, b = slope.
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What is the formula for the Least Squares Regression Line?
ŷ = a + bx, where ŷ = predicted y, x = explanatory variable, a = y-intercept, b = slope.
What is the formula for the slope (b) of the LSRL?
$b = r \frac{s_y}{s_x}$, where r = correlation coefficient, sy = standard deviation of y, sx = standard deviation of x.
What is the formula to calculate the y-intercept (a)?
a = ȳ - bx̄, where ȳ is the mean of y and x̄ is the mean of x.
What is the formula for the coefficient of determination (R²)?
$R^2 = \frac{Variance \ of \ y - Sum \ of \ Squared \ Residuals}{Variance \ of \ y}$
What is the formula for the standard deviation of the residuals (s)?
$s = \sqrt{\frac{\sum(y - \hat{y})^2}{n-2}}$
What is the Least Squares Regression Line (LSRL)?
The line that minimizes the sum of the squared residuals.
Define 'residual' in the context of LSRL.
The difference between the observed (actual) y-value and the predicted (ŷ) value.
What does the slope (b) represent in LSRL?
The predicted change in the response variable (y) for every one-unit increase in the explanatory variable (x).
What does the y-intercept (a) represent in LSRL?
The predicted value of the response variable (y) when the explanatory variable (x) is zero.
What is the coefficient of determination (R²)?
The proportion of the variability in the response variable (y) that is explained by the linear relationship with the explanatory variable (x).
What is the standard deviation of the residuals (s)?
Measures the typical distance of the data points from the LSRL.
Explain the concept of minimizing squared residuals in LSRL.
Squaring residuals gives more weight to larger errors and prevents positive and negative residuals from canceling each other out, resulting in a more accurate model.
Explain the meaning of R² = 1.
R² = 1 means there is a perfect linear fit; all data points fall exactly on the regression line.
Why is n-2 used in the formula for the standard deviation of residuals?
We lose two degrees of freedom when we estimate the slope and the y-intercept.
Explain the importance of context when interpreting slope and y-intercept.
Providing context ensures that the interpretation is relevant and meaningful within the specific scenario of the problem. It connects the statistical result to the real-world situation.
Explain what a computer printout provides in regression analysis.
Computer printouts provide key statistics such as the slope, y-intercept, R-squared, and standard deviation of the residuals, aiding in the interpretation and analysis of the regression model.