Researching autocorrelation – past values' influence over present values
In this section, we will learn how to get data errors or residuals from the linear regression model that we want to use as a time-series model to do forecasts. The regression line indicates the trend of data. The Durbin-Watson test uses the errors to see whether there is periodic behavior in the time frame in order to decide whether there is autocorrelation or not.
First, we are going to use the regression function in Excel with the air passenger sales data, as shown in Figure 11.5. We have to enter the parameters in the regression function and specify that we want error results. To do this, go to the Data option in the Data Analysis upper menu and choose Regression.
If you cannot find the Regression option in Data Analysis, you will have to install the Analysis tool pack in Excel. To do this, follow these steps:
- Click the File tab, and then go to the Options | Add-ins category.
- In...