Deanna L. answered • 06/20/20
Electrical engineering major and music lover with MIT degree
Non-probability sampling is a sampling technique where the samples are gathered in a process that does not give all the individuals in the population equal chances of being selected. This means that probability sampling should be totally random and equally likely to be chosen. Since it is nearly impossible to sample everything and everyone, almost every study relies on non-probability sampling on a large enough scale to represent there is enough data to represent the population. From there you have many options based on how much effort and thought you want to put into choosing your sample.
Convenience sampling chooses out of convenience.
Consecutive sampling tries to choose all accessible test subjects.
Quota sampling tries to get an equal representation of all possible test subjects.
Judgmental sampling targets specific subjects.
Snowball sampling asks the first test subject to identify likely test subjects.
All these are good for experimental and pilot studies when true randomization is nearly impossible. You still need probability sampling to get the best data. Hope that helps!
