A calculated line identifies a target or theoretical relationship between variables on the x- and y-axes. You can compare your actual graphed values against this line as you would any other reference line. But, whereas standard reference lines are a straight line at a single value on one scale only, calculated lines can be curves, sloped lines, or complex polylines. Similarly, while you can add a standard reference line by designating a single value on one axis, producing a calculated line requires two columns of values that are used as y- and x-coordinates. The calculated line is plotted along these coordinates. These coordinates may be derived from a function or some other formula.

Calculated lines do not automatically update when you change the coordinates. You must add a new calculated line with the updated coordinates.

For example, you create a scatterplot and you want to add a line drawn with specific coordinates. The calculated line coordinates are (1,2) and (5,6).

C1 | C2 | C3 | C4 |
---|---|---|---|

Weight | Height | X | Y |

3.97 | 3.46 | 1 | 2 |

2.5 | 1.01 | 5 | 6 |

4.2 | 3.73 | ||

2.19 | 2.02 | ||

... | ... |

Follow these steps to enter coordinates for a calculated line and then add the calculated line to a graph.

- To enter the coordinates for a calculated line:
- Name one empty column
`X`and one empty column`Y`. - In the X column, enter the X coordinates. For example, enter
`1`and`5`. - In the Y column, enter the Y coordinates. For example, enter
`2`and`6`.

- Name one empty column
- Create the scatterplot.
- Right-click the scatterplot and choose .
- In Y column, enter
`Y`. - In X column, enter
`X`. - Click OK.