Surveys and Sampling: The Importance of Research Methods
1. Survey and Sampling as the Research Methods
A survey is a research method used to collect data from a target population through communication, typically via questionnaire. It is one of the main primary research methods. Surveys are widely used in social sciences, market research, and politics (for election polling). They can be useful when a population is hard to access, or when researchers want to collect data on a large scale. However, surveys also have some disadvantages, such as the potential for biased results if the questions are not carefully designed, or if the respondents do not answer truthfully.
Sampling is the process of selecting a representative subgroup from a population. Sampling is used in both quantitative and qualitative research, and there are many different types of sampling techniques. The different types of sampling are pure-random, systematic random, stratified, cluster, and purposeful (also called purposive). The type of sampling technique used depends on the research question, the population being studied, and the resources available.
2. Types of Sampling
2.1 Pure-random Sampling
Pure-random sampling is also known as simple random sampling. In this method, each member of the population has an equal chance of being selected for the sample. This can be done by using a random number generator to select members of the population, or by using a table of random numbers. Pure-random sampling is Simple Random Sampling (SRS) without replacement: each member of the population can only be selected once.
2. 2 Systematic Random Sampling
Systematic random sampling is similar to pure-random sampling, but with a few key differences. First, in systematic random sampling, the population is sampled in a systematic way rather than purely randomly. Second, systematic random sampling often uses a list of all members of the population (such as an voter list), which makes it easier to select a representative sample. Finally, systematic random sampling usually involves selecting every Nth member of the population (e.g., every 10th person on the list), which makes it easier to select an unbiased sample because all members of the population have an equal chance of being selected.
2. 3 Stratified Sampling
Stratified sampling is a type of probability sampling where the population is divided into subgroups (called strata) and then a representative sample is selected from each stratum. This type of sampling is often used when there are known differences between subgroups in the population (e.g., men vs women, young vs old). The advantage of stratified sampling is that it can help ensure that each subgroup in the population is represented in the sample. The disadvantage is that it can be difficult to implement if there are many subgroups in the population, or if the subgroups are not easily defined.
2. 4 Cluster Sampling
Cluster sampling is similar to stratified sampling, but instead of dividing the population into strata based on characteristics like age or gender, the population is divided into groups (called clusters) based on location or other factors. Then, a representative sample is selected from each cluster. Cluster sampling is often used when it would be impractical to sample individuals from a large population (e.g., if researchers want to study school children but there are too many schools to visit). The advantage of cluster sampling is that it can be more efficient than other methods, but the disadvantage is that it can introduce bias if the clusters are not representative of the population.
2. 5 Purposeful (Purposive) Sampling
Purposeful sampling is a type of non-probability sampling where the researcher deliberately chooses a sample that is not random. This type of sampling is often used when the researcher has a specific goal in mind, or when the research question is exploratory in nature. The advantage of purposeful sampling is that it can be used to target specific subgroups or areas of interest. The disadvantage is that it can introduce bias into the results if the sample is not carefully chosen.
3. Conclusion
Surveys and sampling are important research methods that allow researchers to collect data from a target population. There are many different types of sampling techniques, and the type that is used depends on the research question, the population being studied, and the resources available.