which of the following requires a parametric model? when to use a regression model how do you get x% of the return from an index what is the value of y_t in gls what is delta ldots what is the average return of a portfolio and its coefficients what is the time variance for calculating the regression coefficients what is the time variation of the coefficient how is the residual variance in the gls model used how to estimate the risk free rate how to calculate y_t of a linear regression what is y_t which parameter is important for the estimation of regression coefficients how to find the coefficient of return of the portfolio what is the coefficient of the portfolio? how to calculate residuals of regression for y_t how to get x_t$ when to use a parametric model what is the coefficient for the return to market of x_t when calculating a normalized regression, the error terms in each of the following regression terms must be a function of