Majority vote

Majority vote is a quality control method based on matching responses from the majority of Tolokers who complete the same task. For example, if a task has an overlap of “5” and three Tolokers selected the same answer, this is considered indirect confirmation of the correct response.

Note. It only takes into account regular tasks, ignoring the responses to control and training tasks.

Based on the percentage of correct responses, you can change the value of the Toloker's skill or block their access to tasks.

The rule is activated when the task overlap is complete.
Example

Let's say we set up this rule in a pool with overlap=5:



It is activated when at least three of the tasks completed by the Toloker reach full overlap. When responses have been received from all five task Tolokers, the system determines which response was selected by the majority. If the Toloker's responses to two out of three tasks differ from the responses of the majority, the Toloker is banned from the project for 10 days. To collect all the responses needed to trigger the rule, enable Keep task order in the pool settings.



The number of tasks per suite doesn't affect how the rule works. Responses are evaluated separately for each task. Only the speed of collecting results can be affected, because the more tasks you put on each page, the longer it takes to do them.

When to use

Use the Majority vote rule if:
  • You can't regularly create and add control tasks.
  • You want to make an additional review of the Toloker's responses.
Don't use it if:
  • You have a lot of response options.
  • Users need to attach a file to their assignment.
  • Users need to transcribe text.
  • Users need to select objects in a photo.
  • Tasks don't have a correct or incorrect response. For example: “Which image do you like best?” or “Choose the page design option that you like best”.

Usage recommendations

Don't use too many response options or too many questions in the task.

The more options you have, the lower the probability that majority vote will be calculated correctly.

To calculate the majority vote for the task, all the responses to all the questions inside the task must match. If a task has multiple questions or the questions have more than just a few response options, it will be unlikely to have enough exactly matching task responses from different Tolokers in order to calculate the skill. As a result, the task won't be used for skill calculation. If the majority vote hasn't been calculated for the task, the Toloker isn't penalized for mismatching the majority vote.

Example
Toloker 1 Toloker 2 Toloker 3 Toloker 4 Toloker 5
Task 1 OK BAD OK BAD OK
Task 2 BAD OK OK BAD 404
Task 3 404 OK 404 OK OK
Task 4 OK BAD OK 404 404
Task 5 OK BAD OK 404 OK
Toloker 1 Toloker 2 Toloker 3 Toloker 4 Toloker 5
Task 1 OK BAD OK BAD OK
Task 2 BAD OK OK BAD 404
Task 3 404 OK 404 OK OK
Task 4 OK BAD OK 404 404
Task 5 OK BAD OK 404 OK

The requester has five tasks, each completed by five Tolokers. Each task has one output field with three response options. Overlap = 3. In this case, tasks 1, 3, and 5 match the threshold, but the other tasks are not included in the majority vote calculation.

The Tolokers will be assigned the following skills based on majority vote:
Toloker 1 (1+0+1)/3=66% correct
Toloker 2 (0+1+0)/3=33% correct
Toloker 3 (1+0+1)/3= 66% correct
Toloker 4 (0+1+0)/3=33% correct
Toloker 5 (1+1+1)/3=100% correct
Toloker 1 (1+0+1)/3=66% correct
Toloker 2 (0+1+0)/3=33% correct
Toloker 3 (1+0+1)/3= 66% correct
Toloker 4 (0+1+0)/3=33% correct
Toloker 5 (1+1+1)/3=100% correct

Let's say the task Toloker has to select at least three matching categories out of twenty or report that the image is not displayed. Since there can be multiple combinations of categories, the rule calculation will mostly include tasks where all the Tolokers responded Not displayed. Those might be either correct or “fraudulent” responses from Tolokers who just clicked through the tasks in a hurry. In any case, it would be unreliable to base the skill on these responses.

Try using decomposition or control tasks. This way you can better assess the quality of your Tolokers.

Don't set the threshold "Accept as majority" below 50% of the overlap or equal to the overlap.

If the response threshold is equal to the overlap, the rule will only use the tasks where all the Tolokers gave the same responses, ignoring tasks with mismatching votes.

Example
Let's say the pool has overlap=5 and Accept as majority=2. The Tolokers completed the task.
Task response
Toloker 1 OK
Toloker 2 OK
Toloker 3 BAD
Toloker 4 BAD
Toloker 5 404
Task response
Toloker 1 OK
Toloker 2 OK
Toloker 3 BAD
Toloker 4 BAD
Toloker 5 404

In this case, Tolokers 1, 2, 3, and 4 responded correctly, but Toloker 5 failed. However, you don't have any way to know which response is correct.

Don't use the majority vote if:
  • You have a lot of response options.
  • Users need to attach a file to their assignment.
  • Users need to transcribe text or select objects in a photo, or other tasks where the Tolokers can't possibly provide the same responses.

Rule settings

Attention. In this rule, all fields are required except Recent tasks to use. If you don't fill in at least one of them, you won't be able to save the rule.

Field

Overview

Accept as majority

The number of matching responses that is considered the “majority vote” (for example, 3).

Recent values to use

How many recent responses from the Toloker to use.

If this field is not filled in, the calculation includes only task responses from the pool to which the rule is applied.

If the field is filled in, the corresponding number of responses is used. The rule takes into account responses from both the current pool and other pools where this field is filled in.

Learn more about how this field works.

If

A condition for performing the action in the then field:
  • number of responses — The number of completed tasks.

  • % correct answers — The percentage of correct responses, meaning responses that matched the majority opinion (from 0 to 100).

  • % incorrect answers — The percentage of incorrect responses, meaning responses that didn't match the majority opinion (from 0 to 100).

To add multiple conditions, click .

then

Action to perform for the condition:

  • assign skill value — Assign a fixed value to the skill.

  • accept user's answers — Requires the non-automatic acceptance option to be set.

    Useful if the Toloker completes most tasks well. Example: The Toloker completed more than 80% of the tasks correctly and you are satisfied with this result. The rule will work automatically and accept all responses in the pool.

  • suspend — Suspend the Toloker's access to the pool for the specified number of days. Only the requester can view the reason.

  • assign skill from the field — Save the percentage of the Toloker's correct responses in tasks as a skill value.

  • ban — Block access to the project or all of the requester's projects for the specified number of days. Only the requester can view the reason.

    If access to tasks is blocked temporarily (for example, for 7 days), the history of the Toloker's responses is not saved after the ban is lifted. The skill level is calculated based on the new responses.

Field

Overview

Accept as majority

The number of matching responses that is considered the “majority vote” (for example, 3).

Recent values to use

How many recent responses from the Toloker to use.

If this field is not filled in, the calculation includes only task responses from the pool to which the rule is applied.

If the field is filled in, the corresponding number of responses is used. The rule takes into account responses from both the current pool and other pools where this field is filled in.

Learn more about how this field works.

If

A condition for performing the action in the then field:
  • number of responses — The number of completed tasks.

  • % correct answers — The percentage of correct responses, meaning responses that matched the majority opinion (from 0 to 100).

  • % incorrect answers — The percentage of incorrect responses, meaning responses that didn't match the majority opinion (from 0 to 100).

To add multiple conditions, click .

then

Action to perform for the condition:

  • assign skill value — Assign a fixed value to the skill.

  • accept user's answers — Requires the non-automatic acceptance option to be set.

    Useful if the Toloker completes most tasks well. Example: The Toloker completed more than 80% of the tasks correctly and you are satisfied with this result. The rule will work automatically and accept all responses in the pool.

  • suspend — Suspend the Toloker's access to the pool for the specified number of days. Only the requester can view the reason.

  • assign skill from the field — Save the percentage of the Toloker's correct responses in tasks as a skill value.

  • ban — Block access to the project or all of the requester's projects for the specified number of days. Only the requester can view the reason.

    If access to tasks is blocked temporarily (for example, for 7 days), the history of the Toloker's responses is not saved after the ban is lifted. The skill level is calculated based on the new responses.

Examples of rules

Examples are provided for simple classification. There are 10 tasks per suite.

Attention. The assignments submitted by banned Tolokers will be taken into account if they are not rejected manually using assignment review They can be reassigned by setting up the Recompletion of assignments from banned users rule.
Calculating a skill and banning for incorrect responses




Both rules work independently:

  1. If the Toloker gives at least 3 responses to the tasks, the percentage of correct answers is written as the skill value.
  2. If the Toloker gives at least 3 answers to tasks and the percentage of correct answers is less than 65%, they are banned on the project.

The calculation uses up to 10 Toloker's responses to the project tasks.