Editing Cluster sampling (section)

=== Fisheries science ===
It is almost impossible to take a [[simple random sample]] of fish from a population, which would require that individuals are captured individually and at random.<ref>{{cite journal |last1=Nelson |first1=Gary A. |title=Cluster Sampling: A Pervasive, Yet Little Recognized Survey Design in Fisheries Research |journal=Transactions of the American Fisheries Society |date=July 2014 |volume=143 |issue=4 |pages=926–938 |doi=10.1080/00028487.2014.901252|bibcode=2014TrAFS.143..926N }}</ref> This is because [[fishing gear|fishing gears]] capture fish in groups (or clusters). 

In commercial fisheries sampling, the costs of operating at sea are often too large to select hauls individually and at random. Therefore, observations are further clustered by either vessel or fishing trip.