In some types of research the target population might be as broad as all humans, but in other types of research the target population might be a smaller group such as teenagers, pre-school children or people who misuse drugs. It is more or less impossible to study every single person in a target population so psychologists select a sample or sub-group of the population that is likely to be representative of the target population we are interested in. If the sample we select is going to represent the target population then we need to make sure that the people in it are similar to the other members of the target population.
This is important because we want to generalize from the sample to target population. The participants in research, the sample, should be as representative as possible of the target population.
The more representative the sample, the more confident the researcher can be that the results can be generalized to the target population. One of the problems that can occur when selecting a sample from a target population is sampling bias. Sampling bias refers to situations where the sample does not reflect the characteristics of the target population. Many psychology studies have a biased sample because they have used an opportunity sample that comprises university students as their participants e.
But who are you going to try it out on and how will you select your participants? There are various sampling methods. The one chosen will depend on a number of factors such as time, money etc. This is similar to the national lottery. Random samples require a way of naming or numbering the target population and then using some type of raffle method to choose those to make up the sample. Random samples are the best method of selecting your sample from the population of interest.
The advantages are that your sample should represent the target population and eliminate sampling bias, but the disadvantage is that it is very difficult to achieve i. The researcher identifies the different types of people that make up the target population and works out the proportions needed for the sample to be representative. A list is made of each variable e. For example, if we are interested in the money spent on books by undergraduates, then the main subject studied may be an important variable.
For example, students studying English Literature may spend more money on books than engineering students so if we use a very large percentage of English students or engineering students then our results will not be accurate. We have to work out the relative percentage of each group at a university e. Gathering such a sample would be extremely time consuming and difficult to do disadvantage. This method is rarely used in Psychology. However, the advantage is that the sample should be highly representative of the target population and therefore we can generalize from the results obtained.
In quantitative research, the goal would be to conduct a random sampling that ensured the sample group would be representative of the entire population, and therefore, the results could be generalized to the entire population.
The goal of qualitative research is to provide in-depth understanding and therefore, targets a specific group, type of individual, event or process. To accomplish this goal, qualitative research focus on criterion-based sampling techniques to reach their target group. There are three main types of qualitative sampling: The following descriptions describe the reasons for choosing a particular method.
A note on sample size - Once a sampling method has been determined, the researcher must consider the sample size. In qualitative studies, sampling typically continues until information redundancy or saturation occurs. This is the point at which no new information is emerging in the data. Therefore, in qualitative studies is it critical that data collection and analysis are occurring simultaneously so that the researcher will know when the saturation point is reached. It is important to understand that the saturation point may occur prematurely if the researcher has a narrow sampling frame, a skewed analysis of the data, or poor methodology.
Because of this, the researcher must carefully create the research question, select an appropriate target group, eliminate his or her own biases and analyze data continuously and thoroughly throughout the process to bring validity to the data collected. The following slideshare presentation, Collecting Qualitative Data , and the Resource Links on this page provide additional insight into qualitative sampling.
Qualitative Research Methods - A Data Collectors Field Guide - This comprehensive, detailed guide describes various types of sampling techniques and provides examples of each, as well as pros and cons.
Qualitative Research Overview - The following link provides a full overview of qualitative research, but also contains sections discussing types of sampling methods and methods of participant recruitment. Sampling - This resource provides a brief overview of sampling and sample size with links to descriptions of purposeful sampling strategies.
A Guide to Using Qualitative Research Methodology - The file linked below contains a full description of how to conduct qualitative sampling, including a chart that lists the types of sampling techniques and includes examples. Sampling Designs in Qualitative Research - The following article discusses sampling designs and ways to make the sampling process more public.
This pin will expire , on Change. This pin never expires. Select an expiration date. About Us Contact Us. Search Community Search Community. Qualitative Sampling Methods The following module describes common methods for collecting qualitative data. Describe common types of qualitative sampling methodology.
Explain the methods typically used in qualitative data collection. Describe how sample size is determined.
Choosing a sampling method. Techniques > Research > Sampling > Choosing a sampling method. Probability | Quota | Selective | Convenience | Ethnographic | See also. There are many methods of sampling when doing research. This guide can help you choose which method to use.
Sampling Methods. Sampling and types of sampling methods commonly used in quantitative research are discussed in the following module. Learning Objectives: Define sampling and randomization. Explain probability and non-probability sampling and describes the different types of each.
Assumptions of qualitative samplingSocial actors are not predictablelike objects. Randomized events are irrelevant to social life. Probability sampling is expensive Therefore and inefficient. Non-probability sampling is the best approach. Types of samples Sampling is the process of selecting units (e.g., people, organizations) from a population of interest so that by studying the sample we may fairly generalize our results back to .
Multistage Sampling (in which some of the methods above are combined in stages) Of the five methods listed above, students have the most trouble distinguishing between stratified sampling and cluster sampling. Once you know your population, sampling frame, sampling method, and sample size, you can use all that information to choose your sample. Importance As you can see, choosing a sample is a.