In this video, I'd like to show you how to generate the forecast using the regression equation in Excel. So we first copy the coefficients table of the model into this tab and which is here. Then you have two choices. Either you can just type in the regression equation or you use a built-in Excel function. So let's look at the first choice, right, typing in the equation. So we just type in, here is equal and then select intercept plus, then you have to add in the multiplication between the value of the independent variables and their coefficients, one by one. All right here for the first one, So this is the coefficient for time. Then multiply by the value of time, and then plus the coefficient of the price multiply by the value of the price, and then, let's do one more, plus the coefficient of Feb times the value of Feb. All right, and so on and so forth. Now this can be very time consuming if you have a lot of terms in the regression equation. So let me tell you a simple way of doing this. We can use a built-in Excel function, MMULT, to do this quickly. All right. So what you do first is typing equal and then select the intercept. Now this time let's make sure you put a $ sign in front of Q and 28, which is the column and the row label. Because this intercept will not change or is fixed for all the months of 2013. Then we do plus then type in MMULT. Okay. Now you have to select two arrays. The first array is the value of the independent variables, and then put a comma here, and then you select the array of the coefficients. Okay. Because these coefficients are fixed for all the months of the year. So let's put a $ sign in front of both their column and row labels, right, a $ sign here and there and close parenthesis, and here we go. So now, this is the forecast for January 2013. Now, to generate the forecast for all the other months of this year, we just need to drag it down. All right, that's it. But finally, we need to set the right format for these numbers. So next right-click on the selection. Go to format cells. We don't want to have 11 decimal places let's change this to zero, and okay. That's it. I also like to show you how to test the forecast in Excel. We first calculate the absolute errors between the actual value and a forecast. Using the Excel function ABS, open parentheses, actual value minus the forecast, close the parentheses. Then we select this cell and drag it down to get the absolute errors for all the other months. Okay. Now, let's calculate MAD, by taking the average, just type in average, of all the absolute errors. Close parenthesis, which is 121. Finally, let's calculate the MAPD by dividing MAD, right, by the average demand, or the actual values in the first three months.