Hi. This tutorial covers multi-stage sampling. Multi-stage sampling is a sampling technique where any combination of random sampling techniques are used. So it might involve simple random samples. It may involve stratified random samples. It may involve systematic random samples. It may involve cluster samples. So any combination of these random sampling techniques can make up a multi-stage sampling technique.
So let's look at an example of when multi-stage sampling may be useful. Suppose a farmer's interested in the health of trees in his orchard. He stratifies his orchard into eight tree by eight tree squares. He then classifies each row of eight trees as a cluster. He then randomly selects one row of trees per stratum to study.
So let's say that this is the orchard. So what he did first is stratified his orchard. So that would represent one strata, stratum. This would represent another. So each of these are eight by eight, eight trees by eight trees. So he is going to continue this process until he has his farm, his orchard, stratified.
Then what he does is represents each row as a cluster. So we're going to have eight clusters per stratum. So then if he wants to take his sample, what he would need to do is number each cluster within each stratum. So we'll just assume that the top row is always row one. The bottom row is always row eight. So this would be row one down here, row eight. This would be row one here, row eight here.
So then what he would need to do is generate a random number one through eight for each stratum. So let's say here, he randomly selects five. Here, he randomly selects four. Here, he randomly selects one. So for five, the fifth row, those would be the trees that he would study. In the second stratum, row four is the trees he's going to study. Row one-- and he would continue until he has a cluster of trees from each of the nine stratum.
He would then take all of those trees, combine them together into one big sample, that sample being called a multi-stage sample. So since this sampling technique utilizes both stratified random sampling and cluster sampling, it is an example of multi-stage sampling. That is the tutorial on multi-stage sampling. Thanks for watching.