Constructing a Least-Squares Graph Using Microsoft Excel

Simple spreadsheet programs such as Microsoft Excel or Quattro Pro are powerful tools for many types of calculations in chemistry. One of the most often used functions of a spreadsheet program is to construct graphs. The procedure for constructing a least-squares graph using Microsoft Excel is outlined below.

Note that "click" means to put the mouse cursor on a position and press the left mouse button once; to "double-click" means to press the left mouse button twice rapidly; to "drag" means to place the mouse cursor on a position, press and hold the left mouse button, move the mouse cursor to a different position, then release the mouse button. Dragging is used not only to move objects but also to highlight text, data, etc.

1. Enter your data into the spreadsheet. It is often easier to put similar types of data into columns rather than rows (although this is not a requirement).
2. Select (highlight) the data that you want to include in the graph. For example, if you want to plot the data contained in cells 1-4 of columns A and B, place the mouse cursor on cell A1 and drag the mouse cursor to cell B4.

   If the data you want to include happen to be in two columns that are not adjacent (e.g., cells 1-4 of columns A and C), place the mouse cursor on cell A1 and drag the mouse cursor to cell A4. Then, while holding down the CTRL key on the keyboard, place the mouse cursor on cell C1 and drag to cell C4. Both columns of data should be highlighted.

3. Click on Insert on the menu bar.
4. Click on Chart....
5. Under Standard Types, Chart type:, click on XY (Scatter).
6. Under Chart sub-type:, click on the chart with only data markers and no lines.
7. Click on Next>.
8. Click on Next>.
9. Under Titles,
1. click in the text box under Chart title: and enter a title for the graph.
2. click in the text box under Category (X) axis: and enter a title for the x-axis.
3. click in the text box under Value (Y) axis: and enter a title for the y-axis.
10. Click on the Gridlines tab. Click in the checkboxes to turn gridlines on or off.
11. Click on the Legend tab. Click in the checkbox next to Show legend to turn the legend on or off. Placement of the legend on the graph can also be selected here.
12. Click on the Data Labels tab. Click on the radio buttons to turn data labels on or off.
13. Click on the Data Table tab. Click in the checkboxes to turn a data table on or off.
14. Click on Next>.
15. Under Place chart:, click on the radio button next to As new sheet:. Enter a name for the graph in the highlighted text box.
16. Click on Finish. At this point you have created an X-Y plot of the data.
    1. Move the mouse cursor to any data point and press the left mouse button. All of the data points should now be highlighted. Now, while the mouse cursor is still on any one of the highlighted data points, press the right mouse button, and click on Add Trendline... from the menu that appears.
    2. From within the Add Trendline window, under Type, click on the box with the type of fit you want (e.g., Linear).
    3. Click on Options at the top of the Add Trendline window.
    4. Click in the checkbox next to Display equation on chart and the checkbox next to Display R-squared value on chart. Do not click on the checkbox next to "Set Intercept = 0".
    5. Click on OK.