Question

Discuss two main types of  non- probalistic sampling ,giving examples on each type.

Answer 1

Non-probability sampling is a sampling technique where the probability of any member being selected for a sample cannot be calculated. It’s the opposite of probability sampling, where you can calculate the probability. In addition, probability sampling involves random selection, while non-probability sampling does not—it relies on the subjective judgement of the researcher.

The probabilities do not have to be equal for a method to be considered probability sampling. For example, one person could have a 10% chance of being selected and another person could have a 50% chance of being selected. It’s non-probability sampling when you can’t calculate the probabilities at all.

Advantages and disadvantages

A major advantage with non-probability sampling is that compared to probability sampling—it’s very cost- and time-effective. It’s also easy to use and can also be used when it’s impossible to conduct probability sampling (e.g. when you have a very small population to work with).

One major disadvantage of non-probability sampling is that it’s impossible to know how well you are representing the population. Plus, you can’t calculate confidence intervals and margins of error. This is the major reason why, if at all possible, you should consider probability sampling methods first.

Types 

• Convenience Sampling: as the name suggests, this involves collecting a sample from somewhere convenient to you: the mall, your local school, your church. Sometimes called accidental sampling, opportunity sampling or grab sampling.
• Haphazard Sampling: where a researcher chooses items haphazardly, trying to simulate randomness. However, the result may not be random at all and is often tainted by selection bias.

 

 

The to main types of non-probalistic samplinng are convenience sampling and Haphazard sampling