# LOGEST

Returns a table of statistics for an exponential curve that best fits a data set.

### Syntax:

LOGEST(yvalues, xvalues, allow_const, stats)

yvalues is a single row or column range specifying the y coordinates in a set of data points.
xvalues is a corresponding single row or column range specifying the x coordinates. If xvalues is omitted it defaults to 1, 2, 3, ..., n
If there is more than one set of x variables, xvalues may be a range with corresponding multiple rows or columns.
LOGEST finds an exponential curve  that best fits the data. With more than one set of variables the curve is of the form .
In order to fit the curve, LOGEST uses linear regression (the "least squares" method) based on the equation .
if allow_const is FALSE the constant a is forced to be one; . If omitted, allow_const defaults to TRUE (a value for a is found).

to  and a are the coeficients for the equation above.
to  are the standard error values for the ln(b) values;  is the standard error value for the  value.
is the determination coefficient RSQ;  is the standard error value for the  estimate.
F is the F statistic (F-observed value); df is the number of degrees of freedom.
is the regression sum of squares;  is the residual sum of squares.

Example:

In the example above, cells A2:B6 contain the x,y values for a set of points. LOGEST(B2:B6,A2:A6,1,1) returns the statistics for a best fit exponential curve through those points.