# WorksheetFunction.Trend method (Excel)

Returns values along a linear trend. Fits a straight line (using the method of least squares) to the arrays known_y's and known_x's. Returns the y-values along that line for the array of new_x's that you specify.

## Syntax

*expression*.**Trend** (*Arg1*, *Arg2*, *Arg3*, *Arg4*)

*expression* A variable that represents a **WorksheetFunction** object.

## Parameters

Name | Required/Optional | Data type | Description |
---|---|---|---|

Arg1 |
Required | Variant |
Known_y's - the set of y-values that you already know in the relationship y = mx + b. |

Arg2 |
Optional | Variant |
Known_x's - an optional set of x-values that you may already know in the relationship y = mx + b. |

Arg3 |
Optional | Variant |
New_x's - new x-values for which you want Trend to return corresponding y-values. |

Arg4 |
Optional | Variant |
Const - a logical value specifying whether to force the constant b to equal 0. |

## Return value

**Variant**

## Remarks

If the array known_y's is in a single column, each column of known_x's is interpreted as a separate variable.

If the array known_y's is in a single row, each row of known_x's is interpreted as a separate variable.

The array known_x's can include one or more sets of variables. If only one variable is used, known_y's and known_x's can be ranges of any shape, as long as they have equal dimensions. If more than one variable is used, known_y's must be a vector (that is, a range with a height of one row or a width of one column).

If known_x's is omitted, it is assumed to be the array {1,2,3,...} that is the same size as known_y's.

New_x's must include a column (or row) for each independent variable, just as known_x's does. So, if known_y's is in a single column, known_x's and new_x's must have the same number of columns. If known_y's is in a single row, known_x's and new_x's must have the same number of rows.

If you omit new_x's, it is assumed to be the same as known_x's.

If you omit both known_x's and new_x's, they are assumed to be the array {1,2,3,...} that is the same size as known_y's.

If const is **True** or omitted, b is calculated normally.

If const is **False**, b is set equal to 0 (zero), and the m-values are adjusted so that y = mx.

For information about how Microsoft Excel fits a line to data, see **LinEst**.

You can use **Trend** for polynomial curve fitting by regressing against the same variable raised to different powers. For example, suppose column A contains y-values and column B contains x-values. You can enter x^2 in column C, x^3 in column D, and so on, and then regress columns B through D against column A.

Formulas that return arrays must be entered as array formulas.

When entering an array constant for an argument such as known_x's, use commas to separate values in the same row, and use semicolons to separate rows.

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