Identify the sampling technique used in each study. Explain yo...

Question

Identify the sampling technique used in each study. Explain your reasoning.

A journalist asks people at a campground about air pollution.

Accepted Answer

Hello there. Today we're going to solve the following practice problem together. So first off, let us read the problem and highlight all the key pieces of information that we need to use in order to solve this problem. A scientist wants to study the water quality of a river. She divides the river into 10 equal sections and collects a water sample from each section. What type of sampling method is this? Awesome. So it appears for this particular problem we're asked to take the information that is provided to us by the prom itself, and we're asked to determine what type of sampling method this particular scientist is using to perform their study. So now that we know that we're ultimately trying to determine what type of sampling method is being used for this particular problem, let's take a moment to read off our multiple choice answers to see what our final answer might be. A is simple random sampling. He is stratified. Samping C is systematic sampling and D is cluster sampling. Awesome. So first off, in order to solve this problem, let's take a moment to define all of our multiple choice answers. So let's define simple random sampling, stratified sampling, systematic sampling, and cluster sampling in order. So starting with simple random sampling, as we should recall, the definition is every individual in the population has an equal chance of being selected. An example of this particular type of sampling would be drawing names from a hat. And this particular use of sampling is best used when the population is small and homogeneous, which is a fancy way of saying it's the same inconsistent throughout. For stratified. Sampling, as we should recall, it's defined as the population is divided into subgroups, strata, based on shared characteristics such as age, gender, location, and a random sample is taken from each subgroup. An example, this particular type of sampling would be sampling students from each grade level within a school. And this particular use of sampling is best used when you want to have representation from all key subgroups. And for systematic sampling, it's defined as, as we should recall, select every K item from a list or ordered population after choosing a random starting point, and an example of this type of sampling would be surveying every 10th person who enters a store. And this particular use of sampling is best used when the population is organized in a list and is fairly uniform. And lastly, for cluster sampling, as we should recall, this particular type of sampling is defined as the population is divided into clusters, often geographically, then entire clusters are randomly selected. And all members of selected clusters are surveyed. An example of this type of sampling would be selecting 3 neighborhoods randomly and then surveying all the households within each of the neighborhoods. And this particular type of sampling is best used when the population is large and spread out geographically. And considering these different types of sampling, or these type of sampling methods, it's now important to consider that, and now we need to apply those different types of sampling to our particular scenario that we're given. So we're told that the river is divided into 10 equal sections, which is a logical and orderly partitioning of the population. And we need to note that a sample is taken from each of these 10 equal sections, which I'll put a little pair of equal signs to note that we're sample we're taking a sample of our river that's been divided into 10 equal sections, and we're taking a sample from each of the 10 equal sections. So, once again noting that a sample is taken from each section, we need to note that these traits are characteristic of systematic sampling. Where data is collected at regular intervals in this particular case, every section across the population, so that will mean that our final answer without a doubt has to be multiple choice answer letter C, which once again is systematic sampling. Thank you so much for watching. Hopefully that helped, and I can't wait to see you in the next video. Bye.

Identify the sampling technique used in each study. Explain your reasoning.
A journalist asks people at a campground about air pollution.

Key Concepts

Sampling Techniques

Convenience Sampling

Bias in Sampling

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