In Exercises 9–20, identify which of these types of sampling i...

Question

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Cormorant Density Cormorant bird population densities were studied by using the “line transect method” with aircraft observers flying along the shoreline of Lake Huron and collecting sample data at intervals of every 20 km (based on data from Journal of Great Lakes Research).

Accepted Answer

All right, hello, everyone. So this question is asking us to identify which of these types of sampling is used below. Random, systematic, convenience, stratified, or cluster. Researchers studying tree growth in a national forest measured the height of trees by selecting sample locations at regular 15 m intervals along a predefined path through the forest. And here we have 5 different answer choices. With each each answer choice being a type of sampling discussed in the beginning of the question stem. So first, to understand the answer to this question, we have to understand the different types of sampling. So let's go through each of our choices and recall facts about their definitions, right? Starting off with option A here, which is random sampling. Now, random sampling, as the name implies, means that every member of the population that's being studied has an equal chance of being selected. For the study itself, right? An example that comes to mind for me at least is drawing names from a hat. Or some kind of container, there's an equal likelihood that. That any given name can be selected from the container. That's random sampling. Up next here is option B, which is systematic sampling. Now systematic sampling. Refers to Using regular intervals. And what I mean by that is that systematic sampling involves selecting. Members of a population at regular intervals, for example, selecting every 2nd subject or every 3rd subject, etc. Up next we have convenience sampling for answers C. Now convenience sampling. Is more so about ease of access. Right, so the main thing to understand about convenience sampling is that it involves selecting subjects that are easiest to reach without randomizing. And now, for options D and E respectively, we have stratified and cluster sampling. I think it's easy to get these two confused, so let's talk about each one, or actually let's talk about both together. So first, What stratified sampling and cluster sampling have in common is that the greater population is first divided into groups. In stratified sampling, those groups are called strata. And in cluster sampling, those groups are called clusters. But the difference between both of these is what happens after these subgroups are made, right? So in stratified sampling, the subgroups, the strata. Are themselves randomly selected so here A random sample is taken from each strata. On the other hand, in cluster sampling, after the clusters are made, entire clusters are included. In sampling, so entire clusters are picked for the study. So now let's go back to the question that we were given. Right. In this particular study, the researchers are measuring the heights of trees by selecting locations along regular 15 m intervals along a specific path. So, a few things come to mind, right? Namely, the fact that these are regular intervals. Along a set path. This aligns with the characteristics of systematic sampling, meaning the correct answer is option B here. And there you have it. So with that being said, thank you so very much for watching, and I hope you found this helpful.

Key Concepts

Sampling Methods

Line Transect Method

Interval Sampling

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