Microsoft Office Tutorials and References

In Depth Information

**Calculating linear regression**

Figure 17-4
The TREND function creates a data series that can be plotted as a line on a chart.

Figure 17-5
TREND can predict the sales figures for months 19, 20, and 21.

The FORECAST function

The FORECAST function is similar to TREND, except it returns a single point along a

line rather than returning an array that defines the line. This function takes the form

=FORECAST(
x, known_y’s, known_x’s
)
.

The
x
argument is the data point for which you want to extrapolate a value. For example,

instead of using TREND, you can use the FORECAST function to extrapolate the value in cell

C23 in Figure 17-5 by using the formula =FORECAST(21, B2:B19, A2:A19), where the
x

argument refers to the 21st data point on the regression line. You can use this function if you

want to calculate any point in the future.