Assignment Sources

Assignment Sources are how you schematize your assignment data for Statsig, and they serve as the input data for determining who is in an experiment, and which treatment they got.

Creating an Assignment Source

To create an assignment source, go to the experiments tab in Statsig and go to the Assignment Sources pane.

An Assignment Source is defined as a SQL query and a mapping of the output columns to specific fields Statsig requires (user identifiers, a timestamp, an experiment identifier, and a group identifier).

Scanning Assignment Sources

Statsig scans assignment sources on-demand and/or on a schedule to find experiment data. These jobs are very quick and identify unique groups, the ID types present in the experiment, and the estimated of users per group.

Once the scan is complete, you can view and create experiments from the Assignment source. The assignment's experience will also populate the Experiment creation flow after the scan completes.

Manage Assignment Sources

In the Assignment Source tab, you can see your Assignment sources and the experiments they're being used in.

Example Data

For experiment assignment sources, Statsig requires information on who was exposed, when, and to what experiment:

Column Type	Description	Format/Rules
timestamp	Required an identifier of when the experiment exposure occurred	Castable to Timestamp/Date
unit identifier	Required at least one entity to which this metric belongs	Generally a user ID or similar
experiment identifier	Required the experiment the exposure was for	Usually an experiment name
group identifier	Required the experimental variant the user was assigned to	Usually a group name
additional identifiers	Optional Entity identifiers for reuse across identifier types
context columns	Optional Fields which can be used to group by and filter results in exploratory queries

For example, you could pull from exposure event logging directly:

timestamp	user_id	company_id	experiment_name	group_name	country
2023-10-10 00:01:01	my_user_17503	c_22235455	ranking_v1_vs_v2	v1	US
2023-10-10 00:02:15	my_user_18821	c_22235455	ranking_v1_vs_v2	v2	CA
2023-10-10 00:02:22	my_user_18821	c_22235455	search UI revamp	control	CA