Toloka documentation

Ways to group tasks in suites

There are several ways to combine uploaded tasks into suites. You can choose the way that works best for you and specify additional settings.

Why this is important

The Toloker receives payment for a task suite, so the labeling cost and quality depend on optimal task distribution.

Set manually

Enter the number of tasks per suite. The order of tasks depends on the Keep task order pool setting.

Smart mixing

Specify how many tasks of each type should be in each task suite. For example, 8 general tasks, 1 training and 1 control task. If necessary, specify the minimum number of tasks for each type in additional settings.

When to use

This method is useful if the created pool:

Sample settings


  • Tasks are divided into lists: regular, control, and training.

  • The number of tasks of the given type that you specified in the settings is added from each list. By default, tasks are randomly selected.

  • Tasks in the suite are mixed up before the page is shown to the Toloker.

  • If there aren't enough general tasks and the Assign partial page option is set, the Toloker is given an incomplete task suite. Please note that the number of control and training tasks in this case must be complete.


If you upload a file via Smart mixing, you won't be able to use other ways of task distribution on the pages in this pool.

After uploading the tasks with smart mixing you will be able to mark up tasks and set selective majority vote checking.

How to distribute tasks as suites

Characteristics/upload type Set manually Smart mixing
To generate task suites, tasks are taken in the order of rows (from top to bottom) in an uploaded file Yes No
Tasks are mixed within a suite No Yes
Task suites are distributed to Tolokers in the same order No Yes
Within identical task suites, control tasks are the same for all Tolokers Yes No

Control tasks

How many control tasks do I need to add?

We recommend adding at least 1% of control tasks in the pool. And for small pools — 5–10%.

Why's that?

Each control task is shown to the Toloker only once. If you use smart mixing, you determine how many control tasks should be in a suite. If each suite contains one control task, then the maximum number of suites that the Toloker can complete is equal to the number of control tasks in the pool. If you increase the number of control tasks in a suite, the number of suites available to the Toloker decreases by the same degree.

There shouldn't be too few pages available. Otherwise:

  • You won't be able to correctly evaluate the quality of the Toloker's responses.
  • The Toloker won't be interested in completing such tasks because they'll spend a lot of time studying instructions but won't earn much.

A large pool with 1% of control tasks (good)

There are 10,000 tasks in the pool, and 100 of them are control tasks (1%). Each suite contains 10 tasks, and 1 of them is a control task. This means a Toloker can complete up to 100 suites.

A small pool with 1% control tasks (bad)

There are 100 tasks in the pool, and 1 of them is a control task (1%). Each suite contains 10 tasks, and 1 of them is a control task. This means each Toloker can only complete 1 suite.

A small pool with 10% control tasks (good)

There are 100 tasks in the pool, and 10 of them are control tasks (10%). Each suite contains 10 tasks, and 1 of them is a control task. This means a Toloker can complete up to 10 suites.

If there are few control tasks in the open pool, add new control tasks.

What for

In a large pool with few control tasks, there might be a situation when a Toloker who has completed a lot of tasks in the project stops getting new task suites. This happens when the Toloker completes all control tasks in the pool.


To filter out Tolokers, use the Control tasks quality control rule. To rank Tolokers by the quality of responses in control tasks, use a skill.

Setting overlap

If you upload tasks from the Toloka interface, infinite overlap is set automatically for control and training tasks, so that there is enough to mark up all general tasks.

You can set the overlap via the Toloka API or use Set manually for task allocation.


Set infinite overlap for control tasks.

If another overlap value is set, control tasks may end during labeling and the pool will stop being labeled.

Tips and recommendations

  • If you used Set manually, you can find out the number of tasks per suite in the pool settings. But some suites may be incomplete.

  • If you uploaded tasks in a different way, you can check how they're grouped into suites in the Toloka interface for requesters. To do this, on the pool page, click filesDownload all tasks. You can use the Toloka API to check task distribution across suites.

See also

For developers


How do I specify smart mixing settings in the interface when uploading a file?

Smart mixing settings are specified for the file rather than for the pool.

The settings specified during the first file upload are applied to all the files that are uploaded to this pool later on.

What is the maximum number of tasks per suite?

It depends on the task. Technically, you can use as many tasks you want.

But Tolokers don't like to take lengthy tasks. They'd rather do 10 tasks that take one minute each than one task that takes 10 minutes.

In addition, if you use a large number of tasks on the page, there might be issues with uploading the files to be labeled. This problem might occur with images.

The third thing to consider is quality control and manual review. If you allow recompletion of assignments by banned Tolokers, you should split the task into smaller parts so that fewer assignments are recompleted. You are more likely to meet your budget this way.

The same task appeared on different pages

The same task may appear on different pages if:

  • Dynamic overlap is used (incremental relabeling, IRL). As an example, let's say there were 5 tasks on a page. For 4 of them, responses coincided and the common response was counted as correct. The fifth task was mixed into another set because it didn't get into the final response and it needs to be “reassessed”.

  • Different tasks have different overlap. Tasks with higher overlap will be additionally shown in sets with the other remaining tasks in the pool.

  • If a quality control rule changes a task's overlap, it will appear in a different set.

How do I upload the file with the accepted assignments back to Toloka for projects with manual review? Where do I find the format of the upload data?

Use the button Upload review results to upload your file. You can see the format here.

Assignments are reviewed in the tasks file.