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Systematic Sampling

Systematic sampling is a method oftaking a 'random' sample. The population has to listed and ordered insome way, then ever nth element of the list is chosen.

In order that any of the first n in thelist 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 whenthe population is too large for simple random number sampling.

Advantages

1. simple to use

2. suitable for large samples

Disadvantages

1. not truly random unless the listitself is randomly ordered, since if the first in the list ischosen, the second may not be. The process of randomly ordering thelist can be arduous for large populations.

2. it can introduce bias if thepopulation is unevenly distributed.

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