For example the basis of quota has been selected as year in the college. Ultimately, it depends on the type of research being conducted, as well as the budget and timeframe for the experiment, when determining which form of sampling would be more effective to implement. In order to select a sample n of students from this population of 10, students, we could choose to use quota sampling , convenience sampling , purposive sampling , self-selection sampling and snowball sampling:. Many confuse sample size with representativeness. To understand more about self-selection sampling, how to create a self-selection sample, and the advantages and disadvantages of this non-probability sampling technique, see the article: 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.

Simple random sampling , Systematic random sampling and Stratified random sampling ]. To try and minimise the potential ethical issues that come with over-sized and under-sized samples , there are instances where you can make sample size calculations to estimate the required sample size to achieve your goals. When thinking about the population you are interested in studying, it is important to be precise. Quick Formulation of Theories Because convenience sampling is fast and easy, researchers can swiftly gather their data and begin to extrapolate theories from the data. If using a non-probability sampling technique , you need to ask yourself whether you are including or excluding units for theoretical or practical reasons. Accessibility of the subjects become a primary factor affecting whether a subject will be selected or not. Problems with gatekeepers can also affect the representativeness of the sample.

Unlike probability dissrrtation, the goal is not to achieve objectivity in the selection of samples, or necessarily attempt to make generalisations i.

It captures wide variations ranging from typical conditions to extremest conditions. As a result, researchers following a quantitative research design often feel that they are forced to use non-probability sampling techniques because of some inability to use probability sampling e.

# Non-probability sampling | Lærd Dissertation

In addition, you need to decide whether non-probability sampling is appropriate based on the research strategy you have chosen to guide your dissertation. When sampling, you need to decide what units i.

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: 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.

Each of these purposive sampling techniques has a convrnience goal, focusing on certain types of units, all for different reasons. There is no concern for bias convenince into the data, as all participants are randomly selected.

## Non Probability sampling & its types

This can be seen in both of our examples, whether the 10, students we were studying, or the employees at the large organisation. 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.

The more sure we want to be, the larger the sample size needs to be. 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. This has caused significant debate about the validity of results. For example, to select a sample of 25 dorm rooms in your college dorm, make a list of all the room numbers in the dorm. This allows for a great ease of research, letting researchers focus on analyzing the data rather than interviewing and carefully selecting each participant.

For example, you may choose to select only those units to be included in your sample that you feel will disseertation the problem or issue you are interested in finding. 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. Non-probability sampling focuses on sampling techniques that are based on dissetation judgement of the researcher [see our article Non-probability sampling to learn more about non-probability sampling].

This means you select dorm room 3 as your first room, and then every fourth room down the list 3, 7, 11, 15, 19, disswrtation. In both cases, a convenience sample can lead to the under-representation or over-representation of particular groups within the sample. This could mean stopping people in a street corner as they pass by or surveying passersby in a mall.

Similarly, if the confidence level increases, the sample size will need to increase. Let’s say that the university has roughly 10, students.

You intended to collect your data using a survey. Advantages of convenience sampling Convenience sampling is vey easy to carry out with few rules governing how the sample should be collected.

Despite this, for cconvenience following a quantitative research designnon-probability sampling techniques can often be viewed as an inferior alternative to probability sampling techniques.

This type of sampling would be used when accuracy is a must. Theoretical reasons Non-probability sampling represents a valuable group of sampling techniques that can be used in research that follows qualitativemixed methods sanpling, and even quantitative research designs.

In case of snowball sampling, the researcher tries to find one or two such units and then uses them to find more such units till the sample size is met. First, are we doing a true experimental design e.

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 its basic form, convenience sampling method can be applied by stopping random people on the street and asking questionnaire questions.

# Non-probability sampling | Lærd Dissertation

To understand more about snowball sampling, how to create a snowball sample, and the advantages and disadvantages of this non-probability sampling technique, see the article: When we come to describe our population further, we would also need to define what we meant by frequent users e. This is especially the case for convenience sampling. At the same time, you have a duty not to fail to achieve what you set out to achieve.