How to Create a Lag Function in Excel

A lag function allows you to retrieve the value of a cell that is a specified number of rows or columns behind the current cell. While Excel does not have a built-in lag function, you can create one using the OFFSET or INDEX functions. Here's how:

Using OFFSET Function

1. Open Microsoft Excel and enter your data in a worksheet. For this example, let's assume you have a series of values in column A starting from cell A1.
2. In the adjacent column (Column B), click on the cell where you want to display the lag value (e.g., B1).
3. Type the following formula to create a lag function using OFFSET: =OFFSET(A1, -1, 0). Here, -1 is the number of rows you want to lag. You can change this to any number depending on your requirement. The last '0' indicates no offset in the columns.
4. Press Enter, and Excel will display the value from one row above the current cell (A1) in cell B1.
5. Copy the formula in cell B1 and paste it into the cells below B1 to apply the lag function to the entire column.

Using INDEX Function

1. Open Microsoft Excel and enter your data in a worksheet. For this example, let's assume you have a series of values in column A starting from cell A1.
2. In the adjacent column (Column B), click on the cell where you want to display the lag value (e.g., B1).
3. Type the following formula to create a lag function using INDEX: =INDEX(A:A, ROW(A1) - 1). Here, ROW(A1) - 1 is the number of rows you want to lag. You can change this to any number depending on your requirement.
4. Press Enter, and Excel will display the value from one row above the current cell (A1) in cell B1.
5. Copy the formula in cell B1 and paste it into the cells below B1 to apply the lag function to the entire column.

Example

Consider the following table with a series of values in column A:

To create a lag function with a lag of 1 row, follow these steps:

1. In cell B1, type the following formula using the OFFSET function: =OFFSET(A1, -1, 0) or using the INDEX function: =INDEX(A:A, ROW(A1) - 1).
2. Press Enter to see the result. Since there is no value above A1, the result in B1 will be #REF! or 0.
3. Copy the formula in cell B1 and paste it into cells B2, B3, and B4.

The result will look like this:

Column B now displays the lagged values from column A with a lag of 1 row.