This is called sampling. The group from which the data is drawn is a representative sample of the population the results of the study can be generalized to the population as a whole. The sample will be representative of the population if the researcher uses a random selection procedure to choose participants. The group of units or individuals who have a legitimate chance of being selected are sometimes referred to as the sampling frame.
If a researcher studied developmental milestones of preschool children and target licensed preschools to collect the data, the sampling frame would be all preschool aged children in those preschools. Students in those preschools could then be selected at random through a systematic method to participate in the study. This does, however, lead to a discussion of biases in research. For example, low-income children may be less likely to be enrolled in preschool and therefore, may be excluded from the study.
Extra care has to be taken to control biases when determining sampling techniques. There are two main types of sampling: The difference between the two types is whether or not the sampling selection involves randomization. Randomization occurs when all members of the sampling frame have an equal opportunity of being selected for the study.
Following is a discussion of probability and non-probability sampling and the different types of each. Probability Sampling — Uses randomization and takes steps to ensure all members of a population have a chance of being selected. There are several variations on this type of sampling and following is a list of ways probability sampling may occur:. Non-probability Sampling — Does not rely on the use of randomization techniques to select members.
This is typically done in studies where randomization is not possible in order to obtain a representative sample. Bias is more of a concern with this type of sampling. The different types of non-probability sampling are as follows:.
The following Slideshare presentation, Sampling in Quantitative and Qualitative Research — A practical how to, offers an overview of sampling methods for quantitative research and contrasts them with qualitative method for further understanding. Examples of Data Collection Methods — Following is a link to a chart of data collection methods that examines types of data collection, advantages and challenges. Qualitative and Quantitative Data Collection Methods - The link below provides specific example of instruments and methods used to collect quantitative data.
Sampling and Measurement - The link below defines sampling and discusses types of probability and nonprobability sampling. Identify the population of interest. A population is the group of people that you want to make assumptions about. For example, Brooke wants to know how much stress college students experience during finals.
Her population is every college student in the world because that's who she's interested in. Of course, there's no way that Brooke can feasibly study every college student in the world, so she moves on to the next step. Specify a sampling frame. A sampling frame is the group of people from which you will draw your sample. For example, Brooke might decide that her sampling frame is every student at the university where she works. Notice that a sampling frame is not as large as the population, but it's still a pretty big group of people.
Brooke still won't be able to study every single student at her university, but that's a good place from which to draw her sample. Specify a sampling method. There are basically two ways to choose a sample from a sampling frame: There are benefits to both. Basically, if your sampling frame is approximately the same demographic makeup as your population, you probably want to randomly select your sample, perhaps by flipping a coin or drawing names out of a hat.
But what if your sampling frame does not really represent your population? For example, what if the school where Brooke works has a lot more men than women and a lot more whites than minority races? In the population of every college student in the world, there might be more of a balance, but Brooke's sampling frame her school doesn't really represent that well.
In that case, she might want to non-randomly select her sample in order to get a demographic makeup that is closer to that of her population.
Determine the sample size. In general, larger samples are better, but they also require more time and effort to manage. If Brooke ends up having to go through 1, surveys, it will take her more time than if she only has to go through 10 surveys.
But the results of her study will be stronger with 1, surveys, so she like all researchers has to make choices and find a balance between what will give her good data and what is practical. Once you know your population, sampling frame, sampling method, and sample size, you can use all that information to choose your sample.
As you can see, choosing a sample is a complicated process. You might be wondering why it has to be that complicated.
Why bother going through all those steps? Why not just go to a class and pull some students out and have them fill out the survey? Why is sampling so important to research? Get access risk-free for 30 days, just create an account. To answer those questions, let's look at an example of an actual study that was done in the mids. A researcher mailed out surveys to a bunch of married women and asked them questions about their marriage.
As you can imagine, this study sent shockwaves through America as husbands looked at their wives and calculated the probability of dissatisfaction or affairs. Those who got the survey, filled it out, and returned it were much more likely to be dissatisfied than those who didn't return it. Maybe those who were happy in their marriage were too busy having fun with their spouse to cheat.
That's why sampling is so important to research. If a sample isn't chosen carefully and systematically, it might not represent the population. And if it doesn't represent the population, then the study can't be generalized to the world beyond the study. Let's go back to Brooke for a moment. She wants to know, in general, how much stress college students experience during finals.
Let's say that she decides to save some time and bypass the normal sampling method. Instead, she just sets up a table outside the mental health office on campus where students go to see counselors.
As students go in or out of the office, she gives them the survey. But in this example, Brooke's sample might end up being only college students who are seeing counselors. They might be more anxious or depressed or high-strung in general, so the stress of finals might hit them particularly hard.
As a result, Brooke's sample doesn't represent the population, and she might end up thinking that college students experience more stress than they actually do. The sample of a study is the group of subjects in the study. Sampling is the process whereby a researcher chooses his or her sample. The five steps to sampling are:. It is important for researchers to follow these steps so that their sample adequately represents their population.
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What is Sampling in Research? In this lesson, we'll look at the procedure for drawing a sample and why it is so important to draw a sample that represents the population. Try it risk-free for 30 days. An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching.
Register to view this lesson Are you a student or a teacher? I am a student I am a teacher. What teachers are saying about Study. Are you still watching? Your next lesson will play in 10 seconds. Add to Add to Add to. Want to watch this again later? Sampling Techniques In Scientific Investigations. Selecting a Problem to Research. What is a Hypothesis? What is a Research Proposal? Multistage, Multiphase, and Cluster Samples. What is Hypothesis Testing?
What Is Social Science Research? The Importance of Understanding Research Methodology. The Importance of Measurement in the Research Process. Research Methods in Psychology: Research Methods in Psychology for Teachers: Information Systems and Computer Applications. The sample of a study can have a profound impact on the outcome of a study.
Sampling Brooke is a psychologist who is interested in studying how much stress college students face during finals. Process So Brooke wants to choose a group of college students to take part in her study. Importance As you can see, choosing a sample is a complicated process. Try it risk-free No obligation, cancel anytime. Want to learn more? Select a subject to preview related courses: Lesson Summary The sample of a study is the group of subjects in the study.
The five steps to sampling are: Identify the population Specify a sampling frame Specify a sampling method Determine the sample size Implement the plan It is important for researchers to follow these steps so that their sample adequately represents their population. Learning Outcomes Following this lesson, you should have the ability to: Explain what sampling is and its importance to research Describe the five steps to sampling.
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Sampling Methods. Sampling and types of sampling methods commonly used in quantitative research are discussed in the following module. Learning Objectives: Define sampling and randomization. Explain probability and non-probability sampling and describes the different types of each.
Sampling is the process whereby a researcher chooses his or her sample. The five steps to sampling are: The five steps to sampling are: Identify the population.
Research methodologists have developed sampling procedures that should identify a sample that is representative of the population, meaning that the sample closely resembles the target population on all relevant characteristics. In fact, the sampling procedure largely depends on who are your respondents. If it is the general public you may go for random sampling if the the area you are covering is not that large otherwise.
It consist sample definition, purpose of sampling, stages in the selection of a sample, types of sampling in quantitative researches, types of sampling in qualitative researches, and ethical Considerations in . In probability sampling it is possible to both determine which sampling units belong to which sample and the probability that each sample will be selected. The following sampling methods are examples of probability sampling: Of the five methods listed above, students have the most trouble.