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**SSXY**(//dataset //[,//meanX//] [,//meanY//])

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| **SSXY** | Returns the sum of the products of the differences between each data point and its associated (either X or Y) mean value. |
| //dataset// | The label of a QUEUE with its first two component fields defined as REAL. The first component contains the set of X values and the second component contains the set of Y values. |
| //meanX// | A numeric constant or variable containing the average of the X values (optional). |
| //meanY// | A numeric constant or variable containing the average of the Y values (optional). |

**SSXY **computes the sum of the products of the differences between each data point and its associated (either X or Y) mean value. The function operates on the numeric sets defined by all the entries in the first two components of the designated QUEUE (//dataset//). The computation is a significant factor in linear regression formulas.

The optional parameters help to optimize the function. If not provided, the value(s) will be computed internally by the function.

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The passed data set does not have to be sorted. The function copies the passed set. The passed data set is unchanged.

**Return DataType:**    REAL

**Example:**

**StatSetXY QUEUE,PRE()**

**X          REAL**

**Y          REAL**

**          END**

**SumOfSquares   REAL**

**CODE**

** STADAT:Id = STA:Id                 !prime the record buffer**

** STADAT:ItemNumber = 1**

** SET(STADAT:KeyIdItemNumber,STADAT:KeyIdItemNumber !position file pointer**

** LOOP                               !load the QUEUE**

**   NEXT(StatisticsData)             !read next record**

**   IF ERRORCODE() OR STADAT:Id NOT = STA:Id**

**     BREAK**

**   ELSE**

**     StatSetXY:X = STADAT:X         !load the QUEUE buffer**

**     StatSetXY:Y = STADAT:Y         !load the QUEUE buffer**

**     ADD(StatSetXY)                 !add to the QUEUE**

**   END**

** END**

** SumOfSquares = SSXY(StatSetXY)     !call SSXY**