The quality of data and their significance depend crucially on the type of sample design. In principle, two types can be distinguished here: Random samples (probability samples) and non-probability samples. Only random samples allow conclusions to be drawn from the sample to the target population. If this is not the goal of a study, non-probability samples can be a cost-effective alternative.
We are happy to consult you on planning the appropriate sample for your individual research project. The planning of the appropriate sample design as well as the corresponding sample size should be well-considered at the beginning of any survey and tailored to the target population (population), the survey instrument, and the general conditions of the research project (e.g. budget). GESIS supports you in this process by providing advice on sample designs and sample size planning.
Our Consulting Services for your Survey Statistics and Samples
Probability samples provide a basis for drawing conclusions about the target population. The decisive factor is that each unit (such as persons or households) must have a known and positive probability of being included in the sample. We consult you on simple as well as complex random samples and discuss the optimal procedure for your research question.
Non-probability samples are samples that are drawn non-randomly or deterministically. These include quota sampling and the (self-)recruitment of respondents, for example on websites or in social networks. Especially the latter is used more and more frequently in conjunction with the ever-increasing use of online surveys. We consult you on the utilization of non-probabilistic samples for your specific research questions and discuss potential uses and pitfalls.
We have compiled various sets of information and hands-on guidelines on frequently occurring consulting topics. These already answer many questions that may arise when planning a study and collecting data. You can find this information under Basic Knowledge.
Our consulting services in the form of 'helping you to help yourself' are free of charge. Additionally, we are happy to support you with more in-depth services, which are fee-based. You will find further information in our pricing overview. (74 kB)
Here, you can access our form for consulting services. With this form, you can quickly and easily request individual advice from our experts.