The fitted values and residuals have the following properties: a. the sample of the average of the residuals is zero b. the sample covariance between each independent variable and the OLS residual is zero c. the sample covariance between the OLS fitted value and the OLS residual is zero d. All of the above is correct ○ a. a O b. b О с. с O d. d

Find the coefficient of x2y3z3 in the expansion of(x + y + z)8.

Consider the following formula: y i - ( β 0 ^ + β 1 ^ x i ) . What does this formula describe?     OLS slope estimator     Error term     Causal effect of x on y     residual

5.

A large milling machine produces steel rods to certain specifications. The machine is considered to be running normally if the standard deviation of the diameter of the rods is at most 0.42 millimeters. The line supervisor needs to test the machine is for normal functionality. The quality inspector takes a sample of 45 rods and finds that the sample standard deviation is 0.49. What is the test statistic? Select one: а. 59.89 b. 48.63 с. 50.50 d. 52.45

If x; and y; are positively correlated in the sample then the estimated slope is a. equal to zero b. greater than zero c. less than zero d. equal to one