Multistage sampling

Multistage sampling is like picking chocolates from a candy box in different steps. Imagine you have a big box of different types of candy, and you want to have a taste of them all.

First, you can choose a few pieces of each type of candy without looking, but you know they are mostly similar. This is like the first stage of sampling. Then you can pick a few more chocolates from each type of candy, but you can only see some of the pieces. This is the second stage of sampling.

Finally, you can pick a few pieces from each type of candy that you like the most, and you can see each piece before you choose it. This is the last stage of sampling.

In multistage sampling, you pick some samples randomly in different stages from different groups of things. You need to do it this way to get the best results from your sampling. This is because it might not be practical or possible to try to test everything at once. By doing it in stages, you can make it easier to get an accurate idea of what's in the whole box.