how to create a two- variable data table
with Excel
by Gloria Grazioli
Graphs of Two Variables Functions
Many types of economic problems require that we consider two variables at the same time. A typical example is the relation between price of a commodity and the demand or supply of that commodity.
The relation can be described algebraically by a two variable function or equation.
z=f(x;y)
Graphs of Two Variables Functions
The steps below for creating a two-variable data table follow a specific example (rather than using generic steps) to help you understand exactly how to use this feature.
The following slides show a spreadsheet in which two variables function are drawn.
First step
Open your Excel spreadsheet with the quantitative variable information
Label your data set by typing titles into the first row of your lines (column D and row 9). Organize your data so that the data points in column D (x variable) correspond with the data points in row 9 (y variable).
I have two independent variables (inputs: x, y) and one output: z.
set a first value and a step.
It is important to choose an incremente size that is small enough to capture the important features of the graph. If your step size is too coarse, the graph’s shape will be inaccurate
set a value to the two parameters
Second step
Enter the original formula in cell D10.
Click the functional key F4 on keyboard to make the absolute cell address
copy the original formula entered in cell D10 into the range D10:D110
the range of data table includes the formula along the row 8 (value of y-axes)
Third step
Enter the original formula in cell E10.
Click the functional key F4 on keyboard to make the absolute cell address
for a two- variable data table, the copy of the original formula must be entered at the
intersection of the row and column input values
fourth step
Make the graph.
Select the cells E10 through DA110 (both
columns and the labels should be highlighted)
Select the graph (surface) and move it up to the top of the worksheet near the list of values
The graph is a saddle point, named because it looks like the saddle on a horse
