Compare periods

Use this category when you need to compare values across time, such as month-over-month or year-over-year changes.

These functions help you shift values to a reference period and compute absolute or relative deltas.

Start here if…

You want to compare a metric to the previous period, such as month, quarter, year, or week
You want standard growth metrics such as MOM, QOQ, YOY
You want absolute vs relative changes, for example difference vs percentage change
You want compound growth over multiple periods using CAGR

Not here if…

You want cumulative totals or projections → see Rollforward & time series
You need to reshape dimensionality first → see Dimensionality & hierarchies

Mental model

Shift: move values along a time level to align the current period with a reference period
Compare: compute change vs a reference period as an absolute or relative difference
Compound: compute a compounded growth rate from a start value to an end value across multiple periods

Most compare-period functions keep the same output shape as the input node.

Common patterns

Compare to previous year

Use when you want to compute relative year-over-year change.

YOY_REL('Sales')

Compute a generic delta

Use when you want the absolute change along a specific level.

DELTA_ABS('Sales', "Quarter")

Shift values

Use when you need explicit alignment before doing your own arithmetic.

SHIFT('Sales', "Month", -1)

Use period shortcuts

Use when you want a direct previous-period series to combine with operators.

PM('Sales'), PQ('Sales'), PY('Sales'), PW('Sales')

Compound growth over N periods

Use when you want a compounded annual growth rate over N periods.

CAGR('Sales', 3)

Functions in this category

Shift helpers

Function	Description
SHIFT	Shifts values along a specified level by a given offset (positive or negative).
PM	Returns the values for the previous month.
PQ	Returns the values for the previous quarter.
PY	Returns the values for the previous year.
PW	Returns the values for the previous week.

Generic delta functions

Function	Description
DELTA_ABS	Calculates the absolute difference between consecutive values within the selected dimension.
DELTA_REL	Calculates the relative difference between consecutive values within the selected dimension.

Standard period comparisons

Function	Description
MOM_ABS	Returns absolute month-over-month growth compared to the previous month.
MOM_REL	Returns relative month-over-month growth compared to the previous month.
QOQ_ABS	Returns absolute quarter-over-quarter growth compared to the previous quarter.
QOQ_REL	Returns relative quarter-over-quarter growth compared to the previous quarter.
WOW_ABS	Returns absolute week-over-week growth compared to the previous week.
WOW_REL	Returns relative week-over-week growth compared to the previous week.
YOY_ABS	Returns absolute year-over-year growth compared to the previous year.
YOY_REL	Returns relative year-over-year growth compared to the previous year.

Compound growth

Function	Description
CAGR	Calculates the compound annual growth rate over a specified number of periods.

Choosing between similar functions

CAGR vs YOY_REL (or other REL deltas)

Use YOY_REL when you want a single-period relative change vs last year
Use CAGR when you want compounded growth across multiple periods

DELTA_ vs MOM/QOQ/YOY/WOW*

Use MOM, QOQ, YOY, or WOW for common standard comparisons
Use DELTA_ABS or DELTA_REL when you want a delta without filling missing values

ABS vs REL

Use ABS when you need a difference in the same unit as the measure, for example EUR
Use REL when you need a relative change, for example a growth rate

SHIFT vs PM/PQ/PY/PW

Use PM, PQ, PY, or PW when previous month, quarter, year, or week is exactly what you want
Use SHIFT when you need a custom offset or a specific time level

Pitfalls & troubleshooting

Unexpectedly empty output: check whether the reference period exists for those slices and whether missing values propagate through your calculation
Misalignment: confirm the time level you are operating on, for example month vs quarter vs year
CAGR errors or gaps: check whether the start and end values exist for the slice, whether NumberOfPeriods is a whole number greater than or equal to 1, and whether you need a different invalid-handling behavior
Behavior options: if a function supports options such as FirstValueBehavior or MissingValueBehavior, verify which option is active and whether it matches your expectation

Rollforward & time series: running totals, moving windows, projections
Operators: combine current vs reference values using arithmetic and comparisons
Formula basics: evaluation order, constants, and notation
Troubleshooting guide: missing values, wrong shape, unexpected results