In: Statistics and Probability
Suppose you want to conduct a survey of a sample of registered at the University. Discuss some techniques that would be appropriate to select the sample. Discuss the advantages and disadvantages of each.
When the population is small enough, experimenters or researchers have the resources to succeed in resolute all of them. this could be the simplest case situation, ensuring that everyone matters to the survey represent accurately. A survey that covers the whole target population is named a census.
most surveys cannot survey the entire population. This is when sampling techniques become crucial to your survey
there are many sampling techniques given below
(1)- Random Sampling:-
When it is difficult to identify every member of a large
population.then we have to use it. in this type of technique the
entire process of sampling is done in a single step with each
subject selected independently of the other members of the
population.
Pros: In this technique, each member of the population has an equal chance of being selected as subject.
Cons: in case of very large populations, it is difficult to identify every member of the population and the pool of subjects becomes biased. A sample created by doing so might leave out many sections of the population that are significant to the study.
(2)- Systematic Sampling
it is used when population is almost homogenous.
In a systematic sample, first of all we decide n (sample size) then arrange the elements of the population in some order and select terms at regular intervals from the list.
Pros: The main advantage of using systematic sampling over simple random sampling is its simplicity. Another advantage of systematic random sampling over simple random sampling is the assurance that the population will be evenly sampled.
Cons: randomness of the sample is weakness of this technique i.e. an inherent periodicity of the list. This can be avoided by randomizing the list of your population entities, as you would randomize a deck of cards for instance, before you proceed with systematic sampling.
(3)- Quota Sampling
it is used When we can characterize the population based on certain desired characteristics.and assigns a quota to each subset of the population.
Pros: This techniaue can cover several characteristics and varying degrees of complexity.
Cons: Though the method is superior to convenience and snowball sampling, it does not offer the statistical insights of any of the probability methods
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