This is a potential ethical issue. A potential ethical issue Going back to the example of the effect of a carbohydrate free diet on the concentration levels of female university students in the classroom , an under-sized sample does pose potential ethical issues. Each unit in the population is identified, and each unit has an equal chance of being in the sample. The aim was to explore the impact of the Tesco Club card on store loyalty using a sample large enough to demonstrate meaningful results. Non-probability sampling is often used because the procedures used to select units for inclusion in a sample are much easier , quicker and cheaper when compared with probability sampling. Anytime time or money factors into the research, convenience sampling may be used to collect information.
This is one of the basic principles of research ethics. Suppose you want to research the shopping preferences of retail customers of a specific retail brand like Walmart, you can stand at the entrance of a Walmart store and talk to your subjects. Not an ethical issue Imagine that you were interested in the career choices of students at your university , and you were only asking students to complete a questionnaire taking no more than 10 minutes, all an over-sized sample would have done was waste a little of the students’ time. Purposive sampling is also known as judgmental or subjective sampling where you have a specific purpose in mind when you are selecting samples. This highlights the importance of using theory to determine the creation of samples when using non-probability sampling techniques rather than practical reasons, whenever possible. This is a potential ethical issue. Whilst qualitative research designs are more likely to use non-probability sampling techniques, even quantitative research designs that use probability sampling can suffer from issues of reliability associated with gatekeepers.
Another reason for sampling is that not all units in the population can be identified, such as all the air molecules in the LA basin. Each is discussed in turn: Sampling frame The sampling frame is samplign similar to the population you are studying, and may be exactly the same.
Often times this method of sampling is used to gain funding for a larger, more thorough research project. For students doing dissertations at the undergraduate and master’s level, such practicalities often lead to the use of non-probability sampling techniques. If you want to know more about the sampling techniques you may use in your dissertation, read up on probability sampling and non-probability sampling. The convenience sample samplijg suffers from biases from a number of biases. Since the sampling frame is not know, and the sample is not chosen at random, the inherent bias in convenience sampling means that the sample is unlikely to be representative of the population being studied.
This is where an under-sized sample can become an ethical issue. As you’ll know by now, sampling techniques act as a guide to help you select these units, and you will have chosen a specific probability or non-probability sampling technique:. This can be seen in both of our examples, whether the 10, students we were studying, or the employees at the large organisation.
Whilst convenience sampling should be treated with caution, its low cost and ease of use makes it the preferred choice for a significant proportion of undergraduate and master? Then, within in each selected school district, list all the high schools and select a simple saampling sample of high schools.
Cluster sampling is used in large geographic conenience where no list is available of all the units in the population but the population boundaries can be well-defined.
The convenience sample often suffers from biases from a number of biases. Then, you ask 20 of the students to go on a carbohydrate free diet and whilst the remaining 20 continue with the normal food consumption.
When thinking about the population you are interested in studying, it is important to be precise. Did others take part out of kindness or because they had a particular grievance with the organisation? Help Center Find new research papers in: In such cases, it is often more appropriate to refer to each of these e.
The populations of online panels include respondents who are willing to participate in studies, excluding those unwilling to be part of the panel who may be members of the target population we are after.
You decide to spend the two days at the entrance of the organisation where all employees have to pass through to get to their desks. It is predictable, using probability theory.
Was it because some employees were simply congenience busy? Purposive sampling Purposive sampling, also known as judgmentalselective or subjective samplingreflects a group of sampling techniques that rely on the judgement of the researcher when it comes to selecting the units e.
Collectively, these units form the sample that the researcher studies [see our article, Sampling: Non-probability sampling techniques can often be viewed in such a way because units are not selected for inclusion in a sample based on random samlping, unlike probability sampling techniques.
Systematic bias stems from sampling bias. The basicsto learn more about terms such as unitsample and population ]. Convenience sampling is typically only justified if the researcher wants to study the characteristics of people passing by the street corner at a certain point in time, for example. This undermines your ability to make generalisations from your sample to the population you are studying.
This is based on the assumption that we have a list with all the population members population frame and know their probability of being chosen. In practice, your sample may laerc mostly middle class Parisians and the same test in London may well give a different result.
For example, to obtain information about the drug habits of all high school students in a state, you could obtain a list of all the school districts in the state and select a simple random sample of school districts. When thinking about the impact of sampling strategies on research ethics, you need to take into account: Whilst some researchers may view non-probabilit y sampling techniques as inferior to probability sampling techniques, there are strong theoretical and practical reasons for their use.