Systematic sampling is a method of taking a ‘random’ sample. The population has to listed and ordered in some way, then ever nth element of the list is chosen.
In order that any of the first n in the list can be chosen, the first to be chosen may be done randomly – often with random numbers – then every nth one after that.
Systematic sampling may be used when the population is too large for simple random number sampling.
1. simple to use
2. suitable for large samples
1. not truly random unless the list itself is randomly ordered, since if the first in the list is chosen, the second may not be. The process of randomly ordering the list can be arduous for large populations.
2. it can introduce bias if the population is unevenly distributed.