In order to select a sample n of students from this population of 10, students, we could choose to use a convenience sample. Sample size Whether you are using a probability sampling or non-probability sampling technique to help you create your sample, you will need to decide how large your sample should be i. As highlighted in the population examples above, sometimes the populations we are interested in are organisations, institutions and countries. First, you measure their concentration levels. This article discusses the principles of non-probability sampling and briefly sets out the types of non-probability sampling technique discussed in detail in other articles within this site. Your sample size becomes an ethical issue for two reasons:

Use people in the street, people you know, people who work with you, customers and so on. Would this have meant that the performance of 10 students would not have been negatively for a 14 day period as a result? For students doing dissertations at the undergraduate and master’s level, such practicalities often lead to the use of non-probability sampling techniques. Pick any point on the table, and read across or down until you come to a number between 1 and 4. Method Do not worry too much about taking random samples of the population – just use people who are available. So to measure air pollution, you take a sample of air molecules.

We also discuss each of these different types of non-probability samplinh technique, how to carry them out, and their advantages and disadvantages [see the articles: Despite this, we would expect that the likelihood of this happening is fairly low.

This enables you to achieve the sample size you want in a connvenience fast and inexpensive way. When one is considering the use of non probability sampling, he must check if his choice of research strategy fits with the non probability sampling.

laerd dissertation convenience sampling

Perhaps our population is not Facebook usersbut frequent, male Facebook users in the United States. Non Probability sampling unlike probability sampling does not offer all the subjects equal chances of being selected. 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.


After all, you may have a theory that such a problem or issue exists, but there is limited or no research that currently supports such a theory. 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. In both cases, a convenience sample can lead to the under-representation or over-representation of particular groups within the sample.

Non-probability sampling | Lærd Dissertation

When thinking about the population you are interested in studying, it is important to be dissrrtation. For example the basis of quota has been selected as year in the college.

Self-selection sampling is appropriate when we want to allow units or cases, whether individuals or organisations, to choose to take part in research on their own accord.

To get a sense of what these five types of non-probability sampling technique are, imagine that a researcher wants to understand more about the career goals of students at a single university. Sample Size The sample size is simply the number of units in your sample. In our example of the 10, university students, if we were only interested in achieving a sample size of say students, we may simply stand at one of the main entrances to campus, where it would be easy to invite the many students that pass by to take part in the research.

Convenience sampling Convenience sampling is a type of non-probability sampling cobvenience.

laerd dissertation convenience sampling

However, you have read some research showing that such diets can make people feel lethargic i. To understand more about convenience sampling, how to create a convenience sample, and the advantages and disadvantages of this non-probability sampling technique, see the article: Whilst making generalisations from the sample to the population under study may be desirable, it is more often a secondary consideration.

What if you could have come to the same conclusion with fewer students? In our example of the 10, university students, we were only interested in achieving a sample size of students who would take part in our research. Customer transactions at Wal-Mart samplingg Tesco between two time points e. Then, you ask 20 of the students to go on a carbohydrate free samoling and whilst the remaining 20 continue with the normal food consumption.


Types of non-probability sampling There are five types of non-probability sampling technique that you may use when doing a dissertation at the undergraduate and master’s level: Problems of generalisations result because it is not possible to derive statistical inferences from the sample to the population.

Theoretical reasons Non-probability sampling represents a valuable group of sampling techniques that can be used in research that follows qualitativemixed methodsand even quantitative research designs. In the example above, the sample size selected may be just or of the Facebook users that are part of our population of frequent, male, Facebook users in the United States.

Non Probability sampling & its types

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. Did others take part out of kindness or because they had a particular grievance with the organisation? Whilst we discuss more about sampling and why we sample later in this article, the important point to remember here is that a sample consists of only those units in this case, Facebook users from our population of interest i.

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. Therefore, we choose to study just a sample of these Facebook users.

laerd dissertation convenience sampling

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:. If we chose to study these Facebook users using structured interviews i.