File Name: sampling and sample design .zip
It would normally be impractical to study a whole population, for example when doing a questionnaire survey. Sampling is a method that allows researchers to infer information about a population based on results from a subset of the population, without having to investigate every individual. Reducing the number of individuals in a study reduces the cost and workload, and may make it easier to obtain high quality information, but this has to be balanced against having a large enough sample size with enough power to detect a true association. Calculation of sample size is addressed in section 1B statistics of the Part A syllabus.
An introduction to sampling methods
By Saul McLeod , updated In psychological research we are interested in learning about large groups of people who all have something in common. We call the group that we are interested in studying our 'target population'. 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. This is important because we want to generalize from the sample to target population. The more representative the sample, the more confident the researcher can be that the results can be generalized to the target population.
Clinical research usually involves patients with a certain disease or a condition. The generalizability of clinical research findings is based on multiple factors related to the internal and external validity of the research methods. The main methodological issue that influences the generalizability of clinical research findings is the sampling method. In this educational article, we are explaining the different sampling methods in clinical research. In clinical research, we define the population as a group of people who share a common character or a condition, usually the disease. If we are conducting a study on patients with ischemic stroke, it will be difficult to include the whole population of ischemic stroke all over the world.
Learning Skills:. Subscribe to our FREE newsletter and start improving your life in just 5 minutes a day. When you collect any sort of data, especially quantitative data , whether observational, through surveys or from secondary data, you need to decide which data to collect and from whom. There are a variety of ways to select your sample, and to make sure that it gives you results that will be reliable and credible. Ideally, research would collect information from every single member of the population that you are studying. However, most of the time that would take too long and so you have to select a suitable sample: a subset of the population. The idea behind selecting a sample is to be able to generalise your findings to the whole population, which means that your sample must be:.
Methods of sampling from a population
Sign in. Sampling helps a lot in research. If anything goes wrong with your sample then it will be directly reflected in the final result. There are lot of techniques which help us to gather sample depending upon the need and situation.
Published on September 19, by Shona McCombes. Revised on February 25, Instead, you select a sample.