Multi stage sampling
A method of sampling a population where you:
Divide into sub categories
One or more categories chosen
Take part samples of the categories chosen
(Also known as TWO stage cluster sampling)
To summarise think:
i.e. sample categories of sample categories.
To remember this think of the following:
A stage full of SAMPLES were given away at the beginning of the performance. You were given a sample of a sample.
A multi-national bank has over 1000 branches spread over more than 20 countries and wants to conduct a survey of its customers to learn which services they like and dislike. How could they form a sample group comprising 1000 account holders using multi stage sampling?
Stage 1 - Choose 5 countries the bank operates in using simple random sampling (or any other probability sampling).
Stage 2 – Choose 5 branches within each of the selected countries using systematic sampling method (or any other probability sampling).
Stage 3 – Choose 40 account holders to question from each branch using simple random or systematic sampling methods.
This will result in 40 (account holders) x 5 (Branches) x 5 (Countries) = 1000 customers