Menu

AI

Synthetic Data

A practical guide to understanding what synthetic data is and how it is used in AI development.

What synthetic data is, how it is generated, and what product and design teams need to know about its role in training, testing, and evaluation.

5 min read

What it is

Synthetic is artificially generated data that mimics the characteristics of real data without being directly derived from real people or events.

In AI development, synthetic is used to create training examples, evaluation , and test cases where real data is unavailable, too limited, or raises privacy concerns.

For example, a company building an AI for processing customer support might generate thousands of synthetic support conversations to train and evaluate the , rather than using real customer data that would require careful anonymisation and consent management.

Synthetic can be generated by themselves (asking a language model to produce examples of a particular type of input) or through other simulation and generation techniques.

When to use it

Understand when synthetic is a useful approach.

It is most relevant when:

Real training data is scarce or expensive to collect
Privacy regulations restrict the use of real user data
You need a large volume of examples for a specific, well-defined task
You want to generate test cases for edge cases that rarely appear in real data
Evaluation datasets need to cover scenarios that have not yet been observed

It is less relevant when:

Real data is abundant and its use is permissible
The task requires the nuance and variability of genuine human inputs
The synthetic data generation process introduces its own biases

Key takeaway

Synthetic data is a practical tool for supplementing real data, but the quality and representativeness of what is generated determines its value.

How it works

The basic mechanism

Synthetic generation typically starts with a clear specification of what the data should look like: the types of inputs, the range of topics, the expected outputs.

A language can then be used to generate examples matching that specification at scale. These examples are reviewed for quality, filtered for relevance, and used in training or evaluation.

The risk is that if the generator and the being trained share the same underlying , synthetic will reinforce rather than expand capability.

What this means for designers and product teams

Product and design teams contribute most in the specification phase, defining what good examples look like, what should be covered, and what quality standards the generated should meet.

Reviewing synthetic for quality and representativeness is also a product responsibility. Poor synthetic data is worse than no data, because it trains the on incorrect or misleading .

What to look for

Focus on:

Specification quality: whether the generation brief is clear enough to produce useful examples
Coverage: whether the synthetic data covers the full range of inputs the model will encounter
Diversity: whether examples are varied enough to avoid reinforcing narrow patterns
Quality: whether generated examples are realistic and meet the required standard
Bias risk: whether the generation process introduces systematic distortions

Where it goes wrong

Most issues come from: Generating large volumes of low-quality synthetic is not a shortcut. It makes the problem worse.

Vague specifications that produce generic or unhelpful examples
No quality review of generated data before use
Over-reliance on synthetic data in domains where real-world variability matters
Circular bias where the model generates data that reflects its own limitations

What you get from it

Understanding synthetic gives you:

A practical approach to data scarcity problems in AI development
A privacy-preserving alternative to using real user data in some contexts
Better ability to contribute to training data specification and evaluation
More informed decisions about when synthetic data is and is not appropriate

Key takeaway

Synthetic data is only as useful as its specification and quality review. Generated in volume without care, it creates more problems than it solves.

Get in touch

Generated data fills gaps convincingly, which is exactly what makes it risky. We can help you work out where it helps and where it misleads.

No guesswork. No assumptions. Just data you can trust to stand in.

FAQ

Common questions

A few practical answers to the questions that usually come up around this method.

What is synthetic data in AI?

Synthetic data is artificially generated data that mimics the characteristics of real data without being derived from real people or events. It is used to create training examples, test cases, and evaluation datasets where real data is limited, expensive, or raises privacy concerns.

Can synthetic data replace real data?

Not entirely. Synthetic data can supplement real data and help cover gaps, but it typically lacks the unpredictability and genuine variability of real-world inputs. The best AI training pipelines usually combine both.

Is synthetic data safe from a privacy perspective?

Generally yes, because it is not derived from real individuals. However, if synthetic data is generated from a model trained on real data, there is a risk that it encodes patterns that could be traced back to real people. Privacy review is still advisable for sensitive domains.

Who generates synthetic data?

Often engineers or ML teams, using language models or specialised data generation tools. But the specification of what to generate (what types of examples, what edge cases, what quality looks like) is a product and design input. Both sides need to be involved.

What are the risks of using synthetic data?

The main risks are quality and representativeness. If the generated data does not reflect the real variability of user inputs, the model trained on it will have gaps. If the generation process introduces systematic biases, those will be encoded in the model. Both require careful review.

Quick take

Synthetic data lets you train and test AI systems without relying entirely on real user data, which matters for privacy, scale, and speed.

Related Services

LET'S WORK TOGETHER

Ready to improve your product?

UX, research and product leadership for teams tackling complex digital services.

Previous feedback

I had a fantastic experience working with Andy. One of his most impressive achievements during our time at NHS HEE was masterminding a deeply complex information architecture for a new platform that brought together a large number of legacy websites.

Will Parkhouse

Senior Content Designer