Regression Trend Lines
Some of the forecast types you can choose are presented below. All of these forecasts are fit to your data using regression analysis.
Linear forecast with confidence limits
n is a user-supplied constant between 0 and 100 defining the confidence interval. For example, a value of 90 will cause confidence lines to be drawn such that the value being forecast is 90% likely to be between the lines (5% chance of being above the upper line and 5% below the lower). To display lines at one standard deviation from the prediction line, use n = 68.3. To display lines at two standard deviations, use n = 95.5%.
In order for the confidence limits to properly reflect uncertainty in the forecast, the underlying data must conform to assumptions inherent in the linear regression model. Specifically, y must be a linear function of x; and, the residuals must be normally distributed.
n is a user-supplied constant.
p1 and p2 are user-supplied season and cycle periods. All other constants are calculated automatically.