Graduate School of Business
Stanford University
Data Table and Goal Seek in Excel
A model is only an approximation of reality. To derive robust managerial insight from a model,
one should conduct a “What if?” investigation of how the model output varies with uncertain
input parameters. This is commonly called sensitivity analysis. The Data Table command has
Excel evaluate a model output over a range of different values for the input parameters, and
report the results in a table.
For example, in the model below, we want to tabulate the mortgage loan payments that result
from different interest rates. In cell B5 below, PMT is a built-in Excel function to calculate loan
payments. The first argument is the rate per month, the second argument is the number of months
for repaying the loan, and the third argument is the amount of money borrowed, which has a
negative sign because it represents a cash receipt as compared to the loan payment itself, which
is a cash outflow. That is, for convenience the loan payment in this model is considered positive
and so the original loan must have a negative sign to represent the opposite direction of the initial
cash flow. The convention could be reversed with no difference in the calculations, only in the
interpretation of the signs of the numbers. The result returned is the monthly payment. We would
like to conduct a sensitivity analysis to see how interest rates affect the monthly payments, by
using the Data Table command.
1) Fill the Range. List all potential input values in a row or column. In this case, the interest rate
ranges from 9% to 12% in steps of .25% in B8:B20. Then, let cell C7 (just above the first
input value and one cell to the right of the column of values) point to the cell formula in the
model, “=B5”. The labels in B7 and C6 are optional.
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Data Table and Goal Seek in Excel
2) Highlight the range. Click-drag to cover the range B7:C20. Make sure that the range
includes C7, the cell pointing to the model’s performance measure output cell.
3) Activate the Command. Choose the “Data” tab and then choose “What-If Analysis”. Select
“Data Table” from the menu. Since the input values (loan interest rates) are given only in a
column, fill in only “Column Input Cell” box in the Table dialog below. In the box, enter the
cell containing the input value to the model, in this case the cell B2 contains the interest rate.
This tells Data Table which input to vary. Leave the “Row Input Cell” box empty – it would
be used instead if the range of input values were in a row instead of a column. Click OK to
have Excel fill out the table results, as shown below.
The procedure is the same if you want to investigate how an additional model output varies with
the same input. Include another column, D7:D20, with D7 pointing to a different cell formula
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Data Table and Goal Seek in Excel
with B2 as an input variable, and include D7:D20 in the highlighted area. You may add any
number of outputs/columns.
Tabulating With Two Input Parameters
Data Table can tabulate how one model output varies with two different input parameters. Let’s
examine how the loan payment varies with the interest rates and number of monthly payments.
The procedure is the same as above, except that we now have two inputs, B2 and B3.
1) Fill the Range. List all the first input values (from 9% to 12% by .25%) in the column
B8:B20 and all the second input values (from 120 to 600 by 120) in the row C7:G7. Then,
let cell B7 (where the column and the row intersect) point to the model’s performance
measure output cell, “= B5”.
2) Highlight the Range. Click-drag to cover the range B7:G20. Here, make sure that the range
includes B7, the cell pointing to the model’s output cell.
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Data Table and Goal Seek in Excel
3) Activate the Command Choose the “Data” tab and then choose “What-If Analysis”. Select
“Data Table” from the menu. As on the right, fill in the dialog telling Data Table that the
column contains different input interest rates, B2, and the row contains different input
number of payments, B3. Click OK.
(Make sure to check “Calculate Automatically” under “Calculation”)
In both examples, you can transform the Data Table into a graph by selecting all cells in the
table, then clicking on the “Insert” tab, then “Scatter”. In the second example with two inputs,
you can alternatively create a 3-D surface chart. In order to have Solver use your input
parameters as the labels for the 3-D surface chart, you must copy-and-paste the values in the
DataTable, then delete the contents of the upper left cell. Select the new version of the
DataTable and then click on “Insert”, “Other Charts” and “Surface” . The Scatter chart is the
only chart that actually plots X versus Y according to their respective values. Other chart types,
including the 3-D surface chart, treat the inputs as categories and will therefore be distorted
unless the input data are evenly spaced.
The Goal Seek command in Excel searches for a value of a single model input parameter that
results in a specified value of a model output. For example, we can identify the interest rate at
which the monthly payment rate is exactly $2,000 by selecting “Data,” “What-If Analysis,” and
then “Goal Seek” and then entering the monthly payment rate cell B5 into the field “Set Cell”,
entering the number 2000 into the field “To Value” and then entering the interest rate cell B2
into “By Changing Cell”.
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