Numbers, Facts and Trends Shaping Your World

Research in the Crowdsourcing Age, a Case Study

2. The size of the Mechanical Turk marketplace

How many people and organizations use Mechanical Turk? The answer is difficult to determine precisely because key information about the users is proprietary. However, the size of each group can be inferred from a collection of different data sources.

How many people are working specifically on Mechanical Turk?

A 2015 World Bank report estimated Amazon’s Mechanical Turk marketplace has about 500,000 registered workers worldwide, although not all of them are active.

According to – a web tracking company also owned by Amazon – Mechanical Turk had about 750,000 unique visitors worldwide in December 2015 alone.

Of course not all of those visitors participated in the marketplace. Some may have visited to see how the site works. However, the Alexa data give at least circumstantial evidence that many were there to earn money. The average user visited the site almost eight times each in December and spent more than 33 minutes per day there.

How many requesters are posting jobs?

During the period (Dec. 7-11, 2015) examined by Pew Research Center, there were 294 distinct requesters who posted at least once, which translates to an average of about 59 requesters per day. But that is only one way to measure the number of people and groups that are using the site on a regular basis.

According to data collected by Professor Ipeirotis’ mturk-tracker tool, there was an average of 1,278 active requesters per day in 2015. An active requester is defined as a person or group who posted a job on the site before and after the time captured – meaning they had used the site and would continue to do so. In other words, at any given point in 2015, there was an average of 1,278 requesters who had already posted a task on MTurk and would post another in the future.

The high point of use of MTurk by requesters was March 11 when there were 1,634 active requesters.

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