There are two diffierent types of samples:
Representative: Samples that are selected using methods that tries to represent a population.
Non-representative: Samples that are selected using methods that do not try to represent a population.
Known representative methods are: Random, Stratified, Cluster and Systematic, etc.
Non representative method: Convenience.
As we can see the convenience method is a Non-representative method once it requires minimal effort and criteria during the selection which means the sample probably will not represent it's population. So the final answer is Convenience.
