Retrieving HIT status - Amazon Mechanical Turk

Retrieving HIT status

At any point after a HIT is created in Amazon Mechanical Turk (Mechanical Turk) up until it is disposed, you can retrieve the status of a HIT using the GetHIT operation. In addition, you can call ListHITs, ListHITsForQualificationType, or ListReviewableHITs to retrieve HIT information. The HIT data structure returned by these operations includes the attributes and question used to create the HIT, as well as attributes that describe the current status of the HIT.

The most useful attribute to monitor is the HITStatus value, which can be used to evaluate if a HIT is complete. When a HIT is created, its HITStatus initially has a value of Assignable, which indicates that it's possible for a worker to accept it and begin working on it. After the maximum number of assignments have been accepted, the HIT moves to a status of Unassignable because no additional workers can accept it. Finally, a HIT moves to the Reviewable state when all of the assignments have been submitted or the HIT has expired. Keep in mind that you can retrieve interim results at any time, regardless of whether or not all of the HITs have been submitted.

You can use the values NumberOfAssignmentsAvailable and NumberOfAssignmentsPending to monitor assignment acceptance and submission. When a HIT is first created, the number of assignments available is equal to the MaxAssignments value. As HITs are accepted by workers, this number is reduced and the number of assignments pending increases. When workers submit assignments, they are no longer reflected in NumberOfAssignmentsPending. Similarly, if workers return an assignment or the assignment duration elapses, the assignment is no longer reflected in pending but returns to available. When all of the available assignments have been submitted or the HIT expires, the number of pending and available are both 0.

HIT Lifecycle

The following example shows the HIT status values through the lifecycle of a HIT with MaxAssignments set to 5.

Step HITStatus Number Of assignments available Number Of assignments pending
Initial state Assignable 5 0
Three assignments have been accepted Assignable 2 3
All assignments accepted and two submitted Unassignable 0 3
One assignment is returned Assignable 1 2
All assignments submitted Reviewable 0 0
Three of the submitted assignments have been approved Reviewable 0 0
All of the assignments have been approved Reviewable 0 0