Which is a technique of selecting random sampling?
When we sample a population with several strata, we generally require that the proportion of each stratum in the sample should be the same as in the population. Show Stratified sampling techniques are generally used when the population is heterogeneous, or dissimilar, where certain homogeneous, or similar, sub-populations can be isolated (strata). Simple random sampling is most appropriate when the entire population from which the sample is taken is homogeneous. Some reasons for using stratified sampling over simple random sampling are: Simple random sampling is a type of probability sampling technique [see our article, Probability sampling, if you do not know what probability sampling is]. With the simple random sample, there is an equal chance (probability) of selecting each unit from the population being studied when creating your sample [see our article, Sampling: The basics, if you are unsure about the terms unit, sample and population]. This article (a) explains what simple random sampling is, (b) how to create a simple random sample, and (c) the advantages and disadvantages of simple random sampling. Simple random sampling explainedImagine that a researcher wants to understand more about the career goals of students at a single university. Let's say that the university has roughly 10,000 students. These 10,000 students are our population (N). Each of the 10,000 students is known as a unit (although sometimes other terms are used to describe a unit; see Sampling: The basics). In order to select a sample (n) of students from this population of 10,000 students, we could choose to use a simple random sample. With simple random sampling, there would an equal chance (probability) that each of the 10,000 students could be selected for inclusion in our sample. If our desired sample size was around 200 students, each of these students would subsequently be sent a questionnaire to complete (imagining we choose to collect our data using a questionnaire). Creating a simple random sampleTo create a simple random sample, there are six steps: (a) defining the population; (b) choosing your sample size; (c) listing the population; (d) assigning numbers to the units; (e) finding random numbers; and (f) selecting your sample. STEP ONE |