# Documentation/Calc Functions/FORECAST

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## Function name:

FORECAST

## Category:

Statistical Analysis

## Summary:

Extrapolates future values based on existing x and y values.

## Syntax:

FORECAST(**Value**; **DataY**; **DataX**)

## Returns:

Returns a real number which is the predicted value of y using linear regression for the given **Value** and the 2 data sets, **DataY** and **DataX**.

## Arguments:

**Value** is a real number or a reference to the cell containing that number which is the x value, for which the y value on the linear regression is to be returned.

**DataY** is the array or a reference to the range of known y values.

**DataX** is the array or a reference to the range of known x values.

- If
**DataX**has variance of 0 then the function returns a division(#DIV/0!) error. - If dimensions of
**DataX**and**DataY**are not same then the function returns an error value. - If either
**DataX**or**DataY**is an empty array then the function returns an error value and if either of them is a reference to a range of empty cells then the function returns a #VALUE! error.

## Additional details:

- The equation for FORECAST is

y = α + βx,

where α = ӯ - βx̄ and β is given as:

Here x̄ and ӯ are mean values for **DataX** and **DataY**, respectively.

- FORECAST and FORECAST.LINEAR performs the same operation.

## Examples:

DataY | DataX | |
---|---|---|

1 | 195 | 200 |

2 | 151 | 180 |

3 | 148 | 178 |

4 | 189 | 165 |

5 | 183 | 192 |

6 | 154 | 144 |

Formula | Description | Returns |
---|---|---|

=FORECAST(150;A1:A6;B1:B6) | returns the x value expected for the x value of 150 if the DataX (B1:B6) and DataY (A1:A6) values in both references are linked by a linear trend. | 156.839639188173 |

=FORECAST(170;{8,9,10,11};{50,80,110,140}) | returns the y value expected for the x value of 170 if the DataX = {50,80,110,140} and DataY = {8,9,10,11} values in both arrays are linked by a linear trend. |
12 |

## Related LibreOffice functions:

## ODF standard:

## Equivalent Excel functions:

FORECAST