There are different types of random sampling methods which consist of the following:

Stratified sampling- This method consist of the elements in the population are first divided into groups called strata, such that each element in the population belongs to one and only one stratum. After the strata are formed, a simple random sample is taken from each stratum.

Cluster sampling- A probability sampling method in which the population is first divided into clusters and then a simple random sample of the clusters is taken.

Systematic sampling- A probability sampling method in which we randomly select one of the first k elements and then select every kth element thereafter.

Convenience sampling-A nonprobability method of sampling whereby elements are selected for the sample on the basis of convenience.

Judgement sampling-A nonprobability method of sampling whereby elements are selected for the sample based on the judgment of the person doing the study.

If Universities or schools would like to know if there is a difference of wage difference amongst gender the stratified sampling can be used to determine that data. Please discuss with reference