# Time aggregation & relative comparison (e.g. YoY)

In charts and tables, and in the roll-up columns in a spreadsheet, Causal can automatically

**aggregate**a variable's values across time. For example: if your model is monthly and you have a**Revenue**variable, then Causal can automatically summarize the total revenue in each year.The

**Time Aggregation**function lets you choose how this summary is calculated. You can change the method by right-clicking on a variable and selecting**Aggregation Function**from the context menu ->**Time Aggregation,**or if you have Rollup columns toggled on you can click on a rollup cell to easily edit the**Time Aggregation**setting for each variable.time aggregation in the right-click menu of a variable

time aggregation in the roll-up column cells

There are a few options:

**Sum**: this sums up the individual values. Examples:

- Anything that represents a discrete quantity which can accumulate, e.g. "Revenue"

**Average:**this calculates the mean of the individual values. Examples:

- Generally anything that's a percentage, like "Growth rate"

**Final:**this takes the final value in the set of individual values. Examples:

- Anything representing an accumulation, like "Total users" or "Cash in bank"
- A percentage that you expect to move roughly monotonically

**Initial:**just like final, but it takes takes the first value in the set of individual values.

**Formula:**uses the variable's formula to calculate an aggregation value. For example if you have a variable for the

*margin*with the formula

*profit / revenue*, the formula aggregation will take the total profit and divide it by the total revenue of the aggregated period.

Note that the

**Time Aggregation**setting of a variable also determines how a variable is 'rolled up' to a model with a higher-level granularity. For example if you have a Weekly model, and then a Monthly model pulls in a variable from the Weekly model, should it pull the sum, the average, the final...?You can easily compare the value of a variable across relative time periods (e.g. the prior month, the prior year). The comparison is shown on a time aggregated basis too, if relevant. For example, if your model is monthly and you've set your table to Yearly time aggregation, a YoY comparison will show for 2022 vs. 2021, as well as each month (e.g. Jan 2022 vs. Jan 2021).

Last modified 14d ago