Understanding Universe and Sample in Social Research
Understanding the Universe in Social Research
In applied social research, the universe typically refers to the set of individuals that constitute the population being studied. This is especially true when the unit of analysis is the individual, rather than collectives such as homes, families, or businesses.
The universe encompasses all reference elements under study, whether they are individuals, animals, buildings, or objects.
In quantitative surveys, defining the universe is a crucial step, as it serves as the foundation for sampling. While the concept of the universe may sometimes be less emphasized in qualitative research, it’s important to recognize that a reference population exists even when studying people or households.
The assumption that a qualitative sample represents the entire population should not be a barrier to accepting the representativeness of the sample. It’s understood that the sample represents a specific population relevant to the project, and that production data can inform project-specific populations. Statistical probability is not the only basis for generalizing results to a larger population.
Sampling Techniques in Social Research
When working with census data or relatively small population sizes, social research often relies on samples. Here’s a breakdown of sampling practices:
Quantitative Practices
- Emphasis on sample size.
- Detailed description of the sampling process. If the universe is large and heterogeneous, stratification is recommended.
- For stratified samples, information about the relative weight of each stratum is necessary and should be documented in the project.
- For large, complex universes spanning a wide geographical area, multiple sampling methods may be used in successive phases, such as stratified sampling and cluster sampling in the initial stage.
- Consider the data collection instruments: telephone or online surveys allow for random sampling at all stages.
- When using face-to-face questionnaires, the final sample units are often selected through random processes.
- If any stage of sampling is non-random, the overall sampling ceases to be random. This is a critical factor when determining the margin of error.
Qualitative Practices
- Clearly state the criteria guiding the design of samples for interviews or focus groups. For textual analysis, the final sample should include units from each relevant time period.
- In open interviews, the primary criterion is the representativeness of respondents within the field of reality being studied.
Understanding Representativeness in Sampling
The sample size is often determined early in the project planning phase. This decision is influenced by:
- The researcher’s mental image of the sample, considering the number of individuals or groups.
- The relationship between sample characteristics, empirical effort, and time estimates.
After initial consideration, the researcher should refine the targets and samples to ensure alignment with the research objectives.