00:01
In these questions, we want to identify the type of sampling technique.
00:04
So let's start by defining them.
00:06
So we have the simple random sample.
00:12
We have systematic, convenience, stratified, and cluster.
00:29
So starting at the beginning, a simple random sample is where you have your entire population, just a big list of everybody, and you pick from that list completely at random.
00:39
So the important point is each person, has the same chance of being chosen.
00:47
Systematic is where you pick by intervals.
00:50
You pick every nth person in the list.
00:54
Convenience is you do whatever is easiest for you.
00:58
Typically, not very representative, but very cheap to do.
01:01
Maybe you want to sample students at your university, so you just hang around outside the main entrance, ask the first however many people who pass by.
01:10
Not representative, but very easy.
01:13
For the other two, you split.
01:14
Your data up into subgroups based on some kind of shared characteristic.
01:21
Back to your university, maybe it's by their major.
01:25
For stratified, you take a sub sample from each of these proportional to the size of the subgroup.
01:32
That's a lot of effort, but tends to be very representative.
01:35
You know none of the subgroups have been missed out.
01:39
Cluster sampling, you pick entire subgroups.
01:44
Now let's go through these questions.
01:46
Question one.
01:49
A company selects every 25th person.
01:52
Okay, by intervals, that's systematic.
01:57
Question two.
02:00
Nursing supervisors are selected using randomly generated id numbers.
02:04
Okay, it sounds like we're taking from the entire group here...