BIG IDEA 5: IMPACT OF COMPUTING · TOPIC 5.4
5.4 Crowdsourcing
Using the internet to gather help, data, or money from a large, distributed group. Short topic, reliable points.
What you need to know
- Crowdsourcing obtains input, ideas, services, or funding from a large group of people, typically online.
- Citizen science is crowdsourced scientific research: members of the public collect or classify data (bird counts, galaxy classification) that researchers couldn't gather alone.
- The internet makes crowdsourcing possible by connecting large numbers of people cheaply and letting them contribute in small pieces.
- Benefits: scale (thousands of contributors), speed, diversity of input, and lower cost. Some problems are only solvable this way.
- Examples: collaborative encyclopedias, funding platforms, mapping projects, distributed volunteer computing, product reviews, and bug-finding contests.
- Limitations: contributions can be inconsistent in quality, contributors may share biases, and results need verification.
- Crowdsourcing also enables new business and creative models that didn't exist before widespread connectivity.
Worked example
Astronomers have millions of telescope images of galaxies and need each classified by shape. A program can't do it reliably, and one lab would take decades. They post the images online with a simple tutorial; hundreds of thousands of volunteers classify them, each image getting several independent classifications that are compared for agreement. That's citizen science: the crowd provides the labor, the design provides the quality control.
Exam tip: If a scenario involves many members of the public contributing data or effort over the internet toward a shared goal, the answer is crowdsourcing (or citizen science if it's research). Don't confuse it with distributed computing — that's machines sharing work, not people.
Going deeper
The nuance, edge cases, and connections that turn a 3 into a 5.
- Crowdsourcing uses the internet to gather contributions — data, labor, ideas, funding — from a large, distributed group. The CED's point is that the internet makes this possible at a scale and speed that didn't exist before.
- Citizen science is crowdsourcing for research: the public collects or classifies data. Examples: counting birds, classifying galaxy images, recording rainfall, identifying protein structures in a game. The volume of data and geographic coverage would be impossible for professional researchers alone.
- Crowdsourcing enables new business models: crowdfunding (many small contributions fund a project), gig platforms (work distributed to many independent people), and collaborative products (an encyclopedia written by volunteers).
- Quality control is the challenge: contributors vary in skill and care. Solutions include having multiple people do the same task and comparing, reputation systems, expert review of samples, and designing tasks to be simple enough to do reliably.
- Crowdsourcing inherits contributors' biases: if the crowd is mostly one demographic, the data reflects that demographic. This connects to 5.3.
- Crowdsourcing is distinct from distributed computing (4.3): crowdsourcing is many people contributing; distributed computing is many machines. Volunteer computing projects that run on people's home computers blur the line but are technically distributed computing with crowdsourced hardware.
- The CED links crowdsourcing to the broader theme of the internet enabling collaboration among people who never meet — the same idea as 1.1, at planetary scale.
Mistakes that cost points
- Confusing crowdsourcing with distributed computing. People vs. machines. If humans are contributing effort or data, it's crowdsourcing.
- Assuming crowdsourced data is accurate. It needs verification. Options claiming crowdsourcing guarantees accuracy are wrong.
- Missing citizen science. Any scenario where the public helps with scientific data collection is citizen science, even if the word "crowdsourcing" doesn't appear.
Practice questions
Written in the style of the real exam. Try each one before revealing the answer.
Q1 A research group asks the public to photograph and upload pictures of local insects, which the researchers use to track species populations. This is best described as an example of which of the following?
Show answer
Answer: A. Public participation in gathering scientific data is citizen science, a form of crowdsourcing.
Q2 Which of the following is a benefit of crowdsourcing that would be difficult to achieve otherwise?
Show answer
Answer: B. Scale and diversity at low cost is the distinctive benefit. Accuracy and bias still need managing.
Key vocabulary
- Crowdsourcing
- gathering input, work, or funding from a large group of people, usually online
- Citizen science
- scientific research that relies on public volunteers to collect or analyze data