How to Find the Z

1. Open an Excel worksheet and enter your data in one column. For the purposes of this article, enter sample data into cells A1 through A10, typing a different number in each cell.
2. Click on an empty cell below your data and use the “AVERAGE” function to calculate the mean of the numbers you entered. For the example above, you would type “=AVERAGE(A1:A10)” into the formula bar and press 'Enter.' The “A1:A10” part of the formula indicates the range of cells containing the data you want to analyze. The result of the calculation will appear in the cell you selected.
3. Click on a different empty cell below your data and calculate your standard deviation by typing a formula using the function “STDEV” along with your cell range. Continuing the example above, the formula would be '=STDEV(A1:A10)'.
4. Click on an empty cell beside the cell containing the number you want to find the Z-score for. For instance, click on cell B3 if you want to find the Z-score for the number in cell A3. Click the “fx” button on the formula bar to open the “Function” window. Select 'Statistical' from the category dropdown menu, then choose 'STANDARDIZE' to bring up the Function Arguments window.
5. Enter the number you want to calculate the Z-score for in the “X” box. Enter the number itself or a cell reference where the number is located, such as “A3.”
6. Enter the mean you calculated in Step 2 in the “Mean” box. Again, you can type in the number itself, or the cell where you entered the formula in Step 2.
7. Enter your standard deviation in the “Standard_dev” box. Type the number, or the cell where you entered the formula in Step 3.
8. Press “OK” to display the Z-score for the cell you chose in Step 5.