Reading 11 - Correlation and Regression Flashcards
In basic terms, what does covariance measure?
The degree to which two random variables move together
+ means they move together
- means they move in opposite directions
What is the formula to calculate a sample covariance?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/618/252/a_image_thumb.gif?1659420134)
Why is the correlation coefficient a better statistical measure than sample variance?
B/c is converts the covariance into a standardized measure that is easier to interpret
What is Spurious Correlation?
the appearance of a causal linear relationship when, in fact, there is no relation
**May suggest investment strategies that appear profitable but actually would not be**
How do you calculate a sample correlation coefficient for securities X and Y (rXY) ?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/618/860/a_image_thumb.gif?1659420135)
How do you calculate the test statistic(used in a t-test) for the level of significance when given correlation (r) as your data point?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/619/205/a_image_thumb.gif?1659420136)
What are the underlying assumptions in a linear regression?
- A linear relationship exists between the dependent and independent variables
- The independent variable is uncorrelated with the residual return
- The expected value of the residual term is 0
- There is a constant variance of the residual term
- The residual term is independently distributed
- The residual term is normally distributed
What is the sum of squared errors (SSE) ?
& how is it calculated?
The sum of the squared vertical differences between the estimated and actual Y-values
****The regression line is the line that minimizes the SSE
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/619/469/a_image_thumb.gif?1659420137)
How do you calculate the slope term
is equal to the covariance divided by
variance
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/619/552/a_image_thumb.gif?1659420137)
How do you calculate the intercept term?
y - bar = mean of Y
x- bar = mean of X
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/620/889/a_image_thumb.gif?1659420138)
What is the standard error of estimate (SEE)?
the degree of variability of the actual Y-values relative to the estimated Y-values from a regression equation
**SEE gauges the “fit” of the regression line
*** The smaller standard error the better, means the relationship is very strong
What is the coeffficient of determination (R2) ?
The percentage of the total variation in the dependent variable explained by the independent variable.
***R2 can be computed by simply squaring the correlation coeffcient
R2 = r2
What is the formula for the confidence interval for the regression coefficient (b1 hat)?
- b1 hat is the estimated slope coefficient (ie beta)
- tc is the two-tailed test statistic found in the back of the book
- Sb1 is the standard error of the regression coefficient. This is almost always given in the problem
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/621/332/a_image_thumb.gif?1659420139)
What is the formula when using a t-test to test the hypothesis that the true slope coefficient, b1, is equal to some hypothesized value ?
sb1 hat= standard error of the regression coefficient… will be given in the problem.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/083/622/706/a_image_thumb.gif?1659420140)
What are predicted values in an estimated regression model?
Are values of the dependent variable based on the estimated regression coefficients and a prediction about the independent variable.
***They are the values predicted by the regression equation