It is important to note that only some characteristics are not very common, but since it is these characteristics that we are interested in, they influence our choice of total population sampling. Quota sampling , Purposive sampling , Convenience sampling , Snowball sampling and Self-selection sampling ]. Despite this, we would expect that the likelihood of this happening is fairly low. In addition, you need to decide whether non-probability sampling is appropriate based on the research strategy you have chosen to guide your dissertation. These types of bias are quite typical in convenience sampling. This refers to a constant difference between the resultsfrom the sample and the theoretical results from the entire population. Biased Results One of the major drawbacks to this form of sampling is the opportunity for bias to cloud the results of the survey.
Theoretical reasons Non-probability sampling represents a valuable group of sampling techniques that can be used in research that follows qualitative , mixed methods , and even quantitative research designs. It could also mean surveying friends, students, or colleagues that the researcher has regular access to. Another example is using subjects that are selected from a clinic, a class or an institution that is easily accessible to the researcher. Imagine that a researcher wants to understand more about the career goals of students at the University of Bath. Biased Results One of the major drawbacks to this form of sampling is the opportunity for bias to cloud the results of the survey. Would this have meant that the performance of 10 students would not have been negatively for a 14 day period as a result?
However, if the findings from your research are incorrectly taken to reflect the views of all students at your university, and somehow wrongly influence policy within the university e. However, where units are included or excluded for practical reasons, such as ease of access or personal preferences e. This is quite the opposite of probability sampling. If we were to examine the differences in male and female students, for example, the number of students from each group that we would include in the sample would be based on the proportion of male and female students amongst the 10, university students.
Despite this, for researchers following a quantitative research designnon-probability sampling techniques can often be viewed as an inferior alternative to probability sampling techniques.
This is bad from two perspectives, but only one is arguably a potential ethical issue: 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.
Therefore, you want to know whether this is affecting students’ performance; or more specifically, the concentration levels of female students in the classroom.
If this problem or issue does not exist even in your biased sampleit is unlikely to be present if you selected a relatively unbiased sample whether using another non-probability sampling technique; or even a probability sampling technique.
For example, they may control conveniejce access is and is not granted to which individuals, coerce individuals into taking part in your research, and influence the nature of responses.
In order to select a sample n of students from this population of 10, students, we could choose to use quota samplingconvenience samplingpurposive samplingself-selection sampling laaerd snowball sampling:.
The basicsto learn more about terms such as unitrissertation and population ]. A sample is under-sized when you are unable to achieve your goals i.
Sampling bias usually results because election of units being carried out on the basis of ease of access and cost considerations. The manager who has kindly given you access to conduct your research is unable to get permission to get a list of all employees in the organisation, which you would need to use a probability sampling technique such as simple random sampling or systematic random sampling.
Vissertation example, maybe the researcher would avoid approaching certain groups e.
A sample is over-sized when there are more units e. In order to select a sample n of students from this population of 10, students, we could choose to use quota samplingconvenience samplingpurposive samplingself-selection sampling and snowball sampling: For example in case of drug addicts, AIDS patients, domestic violence victims, prostitutes and similar other stigmatised or socially marginalised populations meeting the sample size can be very difficult.
In either case, if no conclusions can be made or the convenince are not statistically significant because the sample size was too small, samling effort, and potential distress and harm that these volunteers put themselves through was all in vein i.
Non Probability sampling & its types
Example 3 The knowledge gains from managers that have been on long-term international assignments in a Fortune company. To learn more about other purposive sampling techniquessee the article: Deciding samplung non-probability sampling is appropriate If you are considering whether to use non-probability sampling, it is important to consider how your choice of research strategy will influence whether this is an appropriate decision.
Let’s look where this may or may not be a problem:.
Non Probability sampling unlike probability sampling does not offer all the subjects equal chances of being selected. This has ethical implications because of the power that such gatekeepers can exercise over those individuals.
Whilst you don’t want to be wasting peoples’ time, and should try and avoid doing so, this is not a major ethical issue. Due to the very small sample sizes and the uncommon characteristics of populations that make up a total population sample, researchers generally look at these samples in-depth using qualitative research methods.
Data analysis techniquesmake sure that you have taken into account: As a researcher, even when you’re an undergraduate or master’s level student, you have a duty not to expose an excessive number of people to unnecessary distress or harm.
Non-probability sampling | Lærd Dissertation
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 selection, unlike probability sampling techniques. These 10, students are our population N. 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:. After all, with the exception of students that just want to help you out, it is likely that most students are taking part voluntarily because they want to the effect of such a diet on their potential classroom performance.
Therefore, you need to check that you have the right to access the list in the first place. Alternately, perhaps they are worried about the effects of such diets, and what to further research in this area.