Local control groups (LCG)
Description
A Local control group (LCG) is the part of a campaign’s audience that does not participate in marketing activities. It is used for precise audience management and for assessing how the campaign affects recipients. At the moment, LCG reporting is not available.
A Global control group (GCG) works across the entire profile database and excludes selected profiles from all activities on the platform. If a profile belongs to the GCG, it cannot participate in a campaign unless that campaign is added to the GCG exception list. GCG is configured in the profile database settings. Details are in the separate GCG article.
LCG setup
Configure the local control group via the Local control group widget on the campaign editor’s main screen by clicking Configure:
Group size setup
Specify the size of the control group in percent. Fractional values are supported:
If you enable Audience limit, you can set the maximum number of profiles for the control group. The actual group size will not exceed this value but may be lower depending on the percentage and available audience.
Recommended LCG size — 5% of campaign audience. Too small a group may not give statistically valid results; too large lowers campaign reach.
Stratification
Description
Stratification is a method of random sampling after splitting the audience into subgroups (strata) based on selected characteristics. The audience is divided so that each subgroup reflects the composition of the full audience.
A share of profiles is selected from each stratum proportional to its size. This creates a control group with the same distribution of characteristics as the test group, which improves accuracy. The maximum number of strata depends on the number of fields and conditions configured in the system.
A stratum is a set of conditions defined by one or more criteria. Each unique combination forms a separate stratum.
A field is a characteristic used to form strata.
It is not recommended to change stratification settings in an active campaign or for an already formed LCG.
Changing values inside fields (adding new cities, expanding age ranges, etc.) may lead to loss of LCG homogeneity — proportions between strata will change, and some current members may move to the test group.
If you change the set of stratification fields (for example, adding stratification by the age field or removing stratification by the region field) — this is a completely different division grid. Current LCG members do not match the new strata, the system cannot map old members to new strata, and moves all of them to the test group. The control group then starts forming from scratch and only from new users.
Stratification example
Suppose the marketer needs to split the audience by three criteria:
- City: Moscow, Saint Petersburg
- Gender: male, female
- Age: 18–30
The system forms strata for all combinations:
- Men aged 18–30 from Moscow
- Men aged 18–30 from Saint Petersburg
- Women aged 18–30 from Moscow
- Women aged 18–30 from Saint Petersburg
Stratum share calculation
Suppose your target audience consists of:
- 50% men, 50% women
- 40% aged 18–30
- 60% from Moscow, 40% from Saint Petersburg
The share of "Men 18–30 from Moscow" in the entire audience:
0.5 × 0.4 × 0.6 = 0.12 (12%)
Profiles for the control group are selected from each stratum proportionally to its share.
Stratification setup
Stratification settings are in the same window as the main LCG parameters and are available via a dropdown menu:
Set strata by one or multiple fields, defining conditions such as date ranges, numeric ranges, or lists of values. The setup is done in the UI, where you can add strata and define parameters for each:
Supported field types
You can use core and additional fields of these types:
- enum — predefined list of values
- bool — true/false
- int/float — numeric values
- string — text
- date — date field
Field conditions
For each type, different conditions are available:
- Number — range ("from–to")
- Float — range with inclusive/exclusive borders
- String — "equals", with multiple values
- Boolean — true, false, missing
- List — "equals", multi-select
- Date — fixed or relative range
Stratification limits
- Minimum conditions per field — 2
- Maximum conditions — 64 total
- Maximum fields — 32
The limit is calculated by multiplying the number of conditions in selected fields.
Example: City (3 values) × Age (2 values) = 6 strata.
Values in one field must not fully overlap:
- Dates — ranges must not overlap
- Numbers — ranges must not fully cover one another
- Strings/lists — no full duplication of values
Strata recommendations
- Up to 100k profiles — 5–10 strata
- 100k–1M profiles — 10–20 strata
- 1M+ profiles — 20–30 strata
Recommended number of conditions per field: 2–4. More than 5 may create overly narrow strata.
Stratification Error
The system may issue a warning if the LCG limit is too small to proportionally fill all strata. The warning does not stop the campaign but indicates that proportions may be violated. For example:
| Parameter | Value |
|---|---|
| Segment | 10,000 profiles |
| LCG | 10% (should be 1,000 profiles) |
| Stratification | Region: Moscow, Saint Petersburg |
| LCG limit | 500 profiles |
Initial distribution
| Stratum | In segment | Share | Expected in LCG (with limit 500) |
|---|---|---|---|
| Moscow | 5,000 | 50% | 250 |
| Saint Petersburg | 5,000 | 50% | 250 |
Proportions are met, no error. Then 5,000 new profiles from Moscow are added to the segment. Now the segment has 15,000 profiles: 10,000 from Moscow, 5,000 from Saint Petersburg.
| Stratum | In segment | Share | Should be in LCG (no limit) | Expected in LCG (with limit 500) |
|---|---|---|---|---|
| Moscow | 10,000 | 66.7% | 1,000 | 333 |
| Saint Petersburg | 5,000 | 33.3% | 500 | 167 |
With an LCG limit of 500, the required LCG size should be 1,500 (10% of 15,000 profiles in the segment). Based on shares of 66.7% and 33.3%, the correct distribution for 500 spots is 333 Muscovites and 167 Petersburgers. The actual LCG composition (250 and 250) does not match this. The LCG cannot be expanded due to the limit, so the system issues a warning.
How to fix: increase the limit to the actual LCG size (at least 1,500) or disable it entirely. In that case, the LCG will be able to add the necessary profiles for the correct proportion during subsequent audience updates.
Ignoring marketing activities
Description
The Ignore marketing activities setting lets you choose activities that must send messages to all profiles, including the control group. Useful for critical communications that must reach everyone.
- Transactional notifications — order status messages
- Legal updates — changes to terms or privacy policy
- Technical alerts — system maintenance messages
- Emergency notifications
Ignore setup
Located in the same LCG settings window:
To edit the list of activities that ignore LCG, click 
Edit:
Audience building process
When you configure LCG and activate the campaign, the system starts the audience building process.
It also starts when LCG settings change in an active campaign.
During audience building:
- Profiles are distributed between the test group and the control group
- Mailings are paused until the process completes
- The campaign receives an additional Audience building status while its main status stays unchanged
If LCG is enabled after the campaign is already active, the control group will contain only profiles added to the campaign after activation, such as through audience expansion. Profiles initially assigned to the test group remain in the test group.
If broadcasts or regular mailings are active when audience building starts, they are paused until it finishes.
LCG management
Once LCG is configured, the following actions are available in the campaign interface:
- Edit settings — change LCG parameters, stratification, and ignored activities;
- Delete LCG — completely remove the local control group. All related settings (Stratification and Ignored Activities) will be deleted along with the LCG. As a result, profiles from the control group will be moved to the test group;
- Export profiles — export LCG participants. After audience building completes, you can select local control group participants for export using filters in the export settings. Export is available in the "Audience" widget. For more details, see here.
Features of the LCG with segment recalculation
When the audience of the segment on which the campaign is based changes, the LCG mechanism has several specific features:
Labeling New Profiles
Audience labeling is triggered automatically after each segment update. The system distributes only the new profiles added to the segment between the test and control groups. Profiles already in the campaign retain their group.
Changing LCG Settings
When control group parameters (percentage or stratification) are changed, or when the LCG is completely deleted, the new settings apply only to new profiles that may be added to the campaign as a result of audience expansion or segment audience updates. Already distributed profiles do not change their group.