A sampling procedure that employs some type of random selection is known as probability sampling. Any element in the population has an equal probability of being picked for inclusion in the sample. Typically, random numbers are employed to choose such sampling. As a result, unbiased population estimates may be obtained by weighting sampled units based on their chance of selection. Discuss the use of the 4 categories of probability sampling as mentioned below, accompanied by relevant examples (unbiased population estimates), and argue which sample is the most unbiased.

(a) Simple random sampling;

(b) Systematic sampling;

(c) Stratified random sampling; and

(d) Cluster sampling.