LINEST() FUNCTION

Trendlines are used to graphically display trends in data and to analyze problems of prediction. Such analysis is also called regression analysis. Trendline are useful but it does not give the error in the slope.

The Linest() function in Excel gives the error (or uncertainty) for data in the lab. It calculates the statistics for a line by using the "least squares" method to calculate a straight line that best fits your data, and returns an array that describes the line. Because this function returns an array of values, it must be entered as an array formula.

An array should be entered in the four boxes. The array represents the following:

Error in the Slope

To determine the +/- error in the slope and the y-intercept, an array must be created. Go back to the original spreadsheet and highlight 4 empty boxes as shown below.

Click the mouse in the formula box and enter the LINEST function.

=LINEST(B2:B12,A2:A12,true,true)

The B2:B12 interval represent the known y values and the A:2:A12 interval represent the x values. The LINEST function will evaluate the errors in the slope and y-intercept for a data set. The const and stats should be labeled true and true as shown below.

IMPORTANT: To enter an array, hold down the

Ctrl and Shift keys at the same time and then press Enter.