how to find a mds value how to find a difference between a Martingale difference and an uncorrelated relationship how do you find serial correlation how to show that serial correlation is true in a martingale difference how do you find the difference between a mds error and a serially correlated error what makes a martingale sequence different what is the mds of the x-t e-t is e_t a martingale difference? is x_t e_t equal to 0 how to find a martingale error if the martingale difference is uncorrelated, does it always occur? what makes a linear distribution uncorrelated where is x_t if a linear model is uncorrelated, what is the value for error? how to prove if the error is a serial correlation what is the serially correlated value of x_t is x_t a martingale error sequence what mds value is given by x_t is x_t an error in the martingale difference sequence how to show that a correlation in error terms makes $x_t