Conducting an empirical study can be quite challenging—especially if you are not exactly sure whom you should actually survey. However, defining the right sample and clearly specifying your research target population is essential to ensure that your results are meaningful. Don’t worry: in this article, you’ll get a simple step-by-step guide to determining your sample.
Why is the sample so important?
Imagine you want to find out how satisfied students are with their studies. If you survey only a handful of fellow students from your circle of friends, you probably won’t get an objective picture. This is exactly where the sample comes in: It ensures that your results can be generalized and are representative.
The sample is therefore the group of people you actually survey in your study. It should reflect your target population as accurately as possible so that you can draw reliable conclusions.
“The quality of an empirical study depends to a large extent on how well the sample matches the target population.”
Dominik E. Froehlich
But how exactly do you define the target population and sample? Here is the step-by-step guide!
1. Specify the research question
Before you can determine the right target population for your research, you need to know exactly what you want to find out. Ask yourself the following questions:
- What exactly do I want to investigate?
- Which people are affected by this topic?
- What characteristics must my respondents have in order to provide relevant answers?
Suppose you want to explore how working from home affects productivity. Relevant characteristics could include:
✔ People who currently work from home
✔ People with professional experience (e.g., not students, but employees)
✔ People from specific industries (e.g., IT, marketing, public administration)
Only once you have formulated your research question precisely can you determine your target population in the next step.
2. Define the target population of the research
The target population of your research includes all those people who could theoretically participate in your study and whose opinions or behavior are relevant to your research question. This group can be very broad or very specific.
To narrow down your target population as effectively as possible, ask yourself the following questions:
- Which demographic characteristics are important? (Age, gender, place of residence, occupation, educational level, etc.)
- Which common interests or experiences should the group have?
- Are there any exclusion criteria? (For example, you may want to survey only full-time employees and not freelancers.)
Once you have defined your target population precisely, you can consider how many people you need for a meaningful sample.
3. Define the sample: How large does it need to be?
The sample size depends on several factors:
- Type of study: A qualitative study often requires fewer participants than a quantitative study.
- Statistical significance: The larger the sample, the more reliable the results.
- Accessibility of the target population: If it is difficult to find suitable people, you may need to accept a smaller sample.
As a general rule: The larger the sample, the better—provided that it is genuinely representative of your target population!
Benchmarks for sample size:
- Qualitative studies (e.g., interviews): 5–30 people
- Surveys with statistical analysis: at least 100–200 people
- Representative studies: 1,000+ people
If you are unsure, you can use a sample size calculator to determine an appropriate sample size.
“A sample that is too small can lead to biased results—and therefore make your entire research project unusable.”
Dominik E. Froehlich
4. Sampling: Random or purposive?
There are various ways to select your sample. Here are the most common methods:
Random sample
Everyone in your target group has the same chance of being selected. This produces particularly objective results, but is often difficult to implement.
✔ Ideal for large online surveys
✔ Particularly representative
✘ Often difficult to implement
Quota sample
You define certain characteristics (e.g., 50% women, 50% men) and deliberately select people to meet these quotas.
✔ Good for balanced samples
✔ Helps avoid bias
✘ Can be time-consuming
Convenience sample
You survey people who are easy to reach (e.g., via social media or personal contacts). Although this method is simple, it is often not very representative.
✔ Simple and quick
✔ Good for exploratory studies
✘ High risk of bias
If you want a sample that is as representative as possible, you should try to use random or quota sampling.
5. Practical tips for recruiting your sample
Once you have defined your sample, it is time to recruit participants. Here are a few tips:
- Online surveys: Platforms such as Google Forms or SurveyMonkey can help you reach many people.
- Social networks: Share your study in relevant Facebook groups, on LinkedIn, or on Twitter.
- Universities & specialist forums: If your target group consists of students or professionals, it is worth looking for participants in relevant forums or university groups.
- Offer incentives: A small incentive (e.g. vouchers or a prize draw) can significantly increase people’s willingness to participate.
“The more clearly you define your target group, the easier it is to find the right participants.”
Dominik E. Froehlich
Conclusion: The right sample makes all the difference
Defining the sample and target group is a crucial step in any empirical study. If you select them carefully, you can ensure that your results are genuinely meaningful. So, in summary:
- Clarify your research question – What do you want to find out?
- Define your target group – Who is relevant to your study?
- Determine the sample size – How many people do you need?
- Choose a sampling method – Randomly or selectively?
- Recruit participants – Where can you find the right people?