LAG

LAG returns a value from a period in the past. 

You could use LAG to calculate how this month's earnings compare to last year's monthly earnings. 

Syntax

LAG(Value to offset, Offset amount, Substitute value [, Non-positive behavior])

Arguments

Note: The LAG keywords are NONSTRICT, SEMISTRICT, or STRICT. 

Syntax example

LAG(Value to offset, 2, 0)

In this example, the LAG 1 line item contains the formula above. This means it returns the value from two periods before.

Since for Jan and Feb, two periods before the cells are outside of the module’s time range, the formula returns the Substitute value of 0. The function does not contain the Non-positive behavior argument, so the default behavior is NONSTRICT.

Additional information

Keywords for non-positive behavior argument:

The LAG mode is set by the keywords, NONSTRICT, SEMISTRICT, or STRICT. The mode controls whether LAG applies to the current period and all past periods, or past periods only.

• NONSTRICT: returns the Value to offset if the Offset amount is positive, negative, or zero.
• SEMISTRICT: returns the Value to offset if the Offset amount is positive or zero. 
• STRICT: returns the Value to offset if the Offset amount is positive. In STRICT mode, LAG applies to the past, and not to current periods. The fill value is returned if either shift < 0 or the past period is beyond model time range.
• If the period LAG specifies is outside of the module's time range, LAG returns the substitute value.
• If a keyword is not included, the behavior defaults to NONSTRICT.

Note: LAG is the opposite of LEAD. Yet the two functions can achieve the same result. If the offset amount of LAG is negative, then the result is the same as LEAD with a positive offset.

Similar functions

• LEAD
• OFFSET

Detailed examples

Example 1

 LAG(Value to offset, 2, 0)

In this example, the LAG line item contains the formula above. This means it returns the value from two periods before each cell.

When the Offset amount specifies a period that falls outside the time range, LAG returns the Substitute value amount, as shown in Jan and Feb columns.

The function does not contain the Non-positive behavior argument, so the default behavior is NONSTRICT.

Example 2

 LAG(Value to offset, 2, Substitute value)

In this example, the LAG line item contains the formula above. This means it returns line item from two periods before each cell.
If the Substitute value amount falls outside the model time range, the value from the Value to offset row in the current period is used, as shown in Jan and Feb columns. The function does not contain the Non-positive behavior argument, so the default behavior is NONSTRICT.

Example 3

 LAG(Value to offset, Offset amount, Substitute value, [Non-positive behavior])

In this example, you can see how the different keywords for the Non-positive behavior change the results.