As an example of XY plotting and fitting, let us consider the example of Ohm's Law:
I have gone to the lab and set up a simple circuit consisting of a voltage supply and a resistor. For a set of voltages, I have measured the corresponding currents through the resistor. The results are in the table below
| V (in volts) | I (in milliamps) |
| 1.00 | 0.238 |
| 2.00 | 0.460 |
| 3.00 | 0.687 |
| 4.00 | 0.909 |
We choose to plot Voltage versus Current, meaning voltages are plotted on the y (vertical) axis and currents are plotted on the x (horizontal) axis. (We make this choice so that the slope of the line we obtain will represent resistance.) To make a so-called XY Scatter plot in Excel, we put the x values in a column and the corresponding y values in the column to the immediate right of it. The next page shows the numbers entered into an Excel spreadsheet.
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