# LinRegVariance (MDX)

Calculates the linear regression of a set, and returns the variance associated with the regression line, y = ax + b.

## Syntax

```
LinRegVariance(Set_Expression, Numeric_Expression_y [ ,Numeric_Expression_x ] ] )
```

## Arguments

*Set_Expression*

A valid Multidimensional Expressions (MDX) expression that returns a set.

*Numeric_Expression_y*

A valid numeric expression that is typically a Multidimensional Expressions (MDX) expression of cell coordinates that return a number that represents values for the y-axis.

*Numeric_Expression_x*

A valid numeric expression that is typically a Multidimensional Expressions (MDX) expression of cell coordinates that return a number that represents values for the x-axis.

## Remarks

Linear regression, that uses the least-squares method, calculates the equation of a regression line (that is, the best-fit line for a series of points). The regression line has the following equation, where a is the slope and b is the intercept:

y = ax+b

The **LinRegVariance** function evaluates the specified setagainst the first numeric expression to obtain the values for the y-axis. The function then evaluates the specified setagainst the second numeric expression, if specified, to obtain the values for the x-axis. If the second numeric expressionis not specified, the function uses the current context of the cells in the specified set as the values for the x-axis. Not specifying the x-axis argument is frequently used with the Time dimension.

After obtaining the set of points, the **LinRegVariance** function returns the statistical variance that describes the fit of the linear equation to the points.

Note

The **LinRegVariance** function ignores empty cells or cells that contain text or logical values. However, the function includes cells with values of zero.

## Example

The following example returns the statistical variance that describes the fit of the linear equation to the points for the unit sales and the store sales measures.

```
LinRegVariance(LastPeriods(10),[Measures].[Unit Sales],[Measures].[Store Sales])
```