If we were only interested in female university students, for example, we would exclude all males in creating our sampling frame, which would be much less than 10, Head teachers of primary schools that had converted to academy status. With random selection, each unit has an equal chance i. First of all, one of the advantages is to reduce human bias by selecting cases included in the sample. Total population sampling Total population sampling is a type of purposive sampling technique that involves examining the entire population i. Typically, we refer to the population of a country or region , such as the United States or Great Britain. Just people in the United States or 62 people in the United Kingdom.

This is perhaps the most challenging criteria affecting the use of probability sampling, which often leads student researchers to use non-probability sampling techniques instead [see the article: This helps to minimise potential sampling bias that would reduce your ability to make generalisations i. This article explains a what purposive sampling is, b the eight of the different types of purposive sampling, c how to create a purposive sample, and d the broad advantages and disadvantages of purposive sampling. 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. Assuming we have chosen a sample size of students, we now need to work out the sampling fraction , which is simply the sample size selected expressed as n divided by the population size N. What is total population sampling?

Non-probability sampling to learn more about non-probability sampling, and Sampling: The sampling frame is very similar to the population you are studying, and may be exactly the same. For example, you want to measure how often residents in New York go to a Broadway show in a given year.

These 10, students are our population N. This article discusses the principles of probability sampling and briefly sets out the types of probability sampling technique discussed in detail in others articles within this site.


There are a number of different types of purposive sampling, each with different goals. Total population sampling is a type of purposive sampling technique that involves examining the entire population i. There are a wide range of purposive sampling techniques that you can use see Patton,; Kuzel,for a complete list.

As discussed earlier in this article, units are the things that make up the population. To minimise sampling bias, probabilistic methods are used so that units from the population are selected at random; the objective is that each unit has an equal chance of being selected. For example, if approaching people in the high street, researchers may consciously choose to approach people that they feel are more like themselves.

However, as can be learnt from probability sampling, being able to get hold of such a population list can be very time consuming and challenging. By contrast, critical case sampling is frequently used in exploratoryqualitative research in order to assess whether the phenomenon of interest even exists amongst other reasons.

These terms can sometimes be used interchangeably.

Maximum variation sampling, also known as heterogeneous samplingis a purposive sampling technique used to capture a wide range of perspectives relating to the thing that you are interested in studying; that is, maximum variation sampling is a search for variation in perspectives, ranging from those conditions that are view to be typical through to those that are more extreme in nature. Homogeneous sampling Homogeneous sampling is a purposive sampling technique that aims to achieve a homogeneous sample; that is, a sample whose units e.

In addition, the systematic random sampling method could undeliberate select the cases which are alike instead of random cases if the population list is in standardized arrangement.

laerd dissertation random sampling

Creating a stratified random sample. Each of the 10, students is known as a unit although sometimes other terms are used to describe a unit; see Sampling: Advantages of purposive sampling Dissertattion are a wide range of qualitative research designs that researchers can draw on.


Simple random sampling | Lærd Dissertation

Purposive sampling explained Types of purposive sampling Advantages and disadvantages of purposive sampling. This list is the sampling frame from which you select units. Creating a total population sample To create a total population sample, there are three steps.

laerd dissertation random sampling

The word typical does not mean that the sample is representative in the sense of probability sampling i. The population size is relatively small In total population sampling, researchers choose to study the entire population because the size of the population that has the particular set of characteristics that we are interest in is typically very small.

Alternately, click on the articles below: We do this using either simple random sampling or systematic random sampling [click on the links to see what to do next]. If our desired sample size was around students, each of these students would subsequently be sent a questionnaire to complete imagining we choose to collect our data using a questionnaire.

Cluster Sampling

Probability sampling helps us to make such statistical inferences and assess how confident we are about such inferences. Now let’s look at each of these basic principles of probability sampling: Conscious and unconscious human choices Researchers have conscious and unconscious biases that can affect how they select units from the population for inclusion in their sample.

Some examples of each of these types of population are present dissdrtation.

The basicsif you are unsure about the terms unitsamplestrata and population ]. By conditionswe mean rndom units i. If you are considering whether to use probability sampling, it is important to consider how your choice of research strategy will influence whether this is an appropriate decision.