Quantitative Methods Flashcards
Covariance definiton and equation
- Covariance – Statistical measure of the degree to which the two variables move together in linear relationship
*
Correlation Coefficient definition and equation and result interpretation
· Correlation coefficient – measure of the strength of linear relationship b/t 2 variables, no units
Spurious correlation definition
i. Spurious correlation – appearance of causal linear relationship when there isn’t one
Nonlinear relationship definition
i. Nonlinear relationship – correlation doesn’t capture nonlinear relationships
t-test if population correlation coefficient equals zero, degrees of freedom equation, accept/reject rules
“statistically significant”
[equation]
[equation]
i. Df = n-2
ii. Reject H0 if +tcritical < t, or t < –tcritica
Linear regression assumptions
i. Linear relationship exists bt dependent and independent variables
ii. Ind. Variable is uncorrelated with the residuals
iii. Expected value of the residual term is zero
iv. Variance of the residual term is constant for all observations
v. Residual term for one observation is not correlated with that of another
vi. Residual term is normally distributed
Linear Regression slope coefficient equation and represents
[equation]
- Represents a stocks systematic risk (beta), value of 1 would be average risk, >1 would be higher risk
Linear regression intercept equation and interpretation
[equation]
- Called “ex-post alpha”, measures excess risk adjusted returns, (-) value means it underperforms
Standard Error Estimate (SEE)
· Degree of variability of actual Y values from regression Y’s
i. Smaller the SEE, better the fit
ii. Standard deviation of residual terms
Coefficient of Determination (R2)
· Percent of the total variation in the dependent variable explained by the independent
i. For simple linear regression: R2 = r2 = (correlation coefficient)2
Regression slope coefficient confidence interval
Is slope significantly different than zero?
[equation]
i. standard error of the regression coefficient is denoted as sˆb1
ii. Df= n -2
iii. If confidence interval does not include zero, then slope/coefficient is significantly different than 0
T - test for regression slope coefficient
[equation]
i. Df = n – 2
ii. Reject H0 if t > + tcritical or t < –tcritical
iii. Rejection of the null means that the slope coefficient is different from the hypothesized value of b1
Confidence interval for predicted values
[equation]
for predicted value of dependent variable
i. tc = two-tailed critical t-value at the desired level of significance with df = n – 2
ii. sf = standard error of the forecast
Total sum of squares (SST)
definition and equation
i. measures total variation in dependent, difference b/t actual and mean Y values
[equation]
Regression Sum of Squares (RSS)
definition and equation
Measures the variation in the dependent variable that is explained by the independent variable, difference b/t predicted Y’s and mean Y
[equation]