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
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.