Snowball sampling
Snowball sampling is a non-probability sampling method in which existing participants help researchers recruit additional participants. It is particularly useful when studying hard-to-reach, hidden, specialised, or restricted populations where no complete sampling frame exists.
On This Page:
- Snowball Sampling Explained Simply
- What is Snowball Sampling?
- Snowball Sampling vs Convenience Sampling
- Types of Snowball Sampling
- How Snowball Sampling Works
- Snowball Sampling in Business Research
- Common Mistakes
- Advantages and Disadvantages of Snowball Sampling
- Snowball Sampling in the Age of AI and Digital Research
- When to Use Snowball Sampling
- Exam Tip
| Aspect | Snowball Sampling | Convenience Sampling |
|---|---|---|
| Participant recruitment | Through referrals | Through availability |
| Suitable for hidden populations | Highly suitable | Usually unsuitable |
| Researcher control | Moderate | Higher |
| Sampling bias | High | High |
| Cost | Usually low | Usually low |
| Generalisability | Limited | Limited |
Snowball sampling vs convenience sampling (comperative table)
Snowball Sampling Explained Simply
Imagine you want to study venture capital investors who specialise in artificial intelligence start-ups. There is no public list containing all such investors. You interview one investor and ask them to introduce you to others in their professional network. Those participants then refer additional investors, and the sample gradually grows.
This is snowball sampling.
A similar approach may be used when studying cryptocurrency traders, senior executives, whistleblowers, luxury club members, startup founders, or employees working in highly specialised industries.
In simple terms, researchers start with a small number of participants and allow the sample to expand through referrals, much like a snowball rolling downhill and increasing in size.
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What is Snowball Sampling?
Snowball sampling, also known as chain-referral sampling, is a non-probability sampling technique in which existing participants identify and recruit additional participants who possess characteristics relevant to the study. Unlike probability sampling methods, not all members of the population have a known chance of selection. Instead, access to new participants depends on referrals from existing participants.
Snowball sampling is particularly useful when:
- the population is difficult to identify
- participants are difficult to access
- no complete sampling frame exists
- trust and personal connections are important
- the population is relatively small or specialised
For example, researchers studying angel investors, elite golf club members, expatriate entrepreneurs, or cybersecurity experts may struggle to identify suitable participants directly. In such cases, referrals often become the most practical recruitment strategy.
Types of Snowball Sampling
Researchers commonly distinguish between three forms of snowball sampling.
1. Linear snowball sampling. Linear snowball sampling begins with a single participant. That participant refers one additional participant. The newly recruited participant then refers one further participant. The process continues until the desired sample size is achieved. This creates a simple chain of referrals.
2. Exponential non-discriminative snowball sampling. In this approach, each participant provides multiple referrals. All referrals may potentially be recruited into the study. As a result, the sample expands rapidly and can grow exponentially. This version is often used when researchers need to recruit participants quickly.
3. Exponential Discriminative Snowball Sampling. Participants again provide multiple referrals. However, researchers selectively recruit only those participants who best fit the study’s aims and objectives. This approach provides greater control over sample composition while still benefiting from referral networks.




