Having established the frame, there are a number of ways for organizing it to improve efficiency and effectiveness. It's at this stage that the researcher should decide whether the sample is in fact to be the whole population and would therefore be a census. This list should also facilitate access to the selected sampling units. A frame may also provide additional 'auxiliary information' about its elements; when this information is related to variables or groups of interest, it may be used to improve survey design.
Here, I want to introduce several different terms for the major groups that are involved in a sampling process and the role that each group plays in the logic of sampling. The major question that motivates sampling in the first place is: We would like to be able to talk in general terms and not be confined only to the people who are in our study.
In that case, sampling and generalizing might not be of interest. In other cases, we would really like to be able to generalize almost universally.
When psychologists do research, they are often interested in developing theories that would hold for all humans. But in most applied social research, we are interested in generalizing to specific groups.
The group you wish to generalize to is often called the population in your study. This is the group you would like to sample from because this is the group you are interested in generalizing to.
If that is the population of interest, you are likely to have a very hard time developing a reasonable sampling plan.
You are probably not going to find an accurate listing of this population, and even Sampling frame you did, you would almost certainly not be able to mount a national sample across hundreds of urban areas. So we probably should make a distinction between the population you would like to generalize to, and the population that will be accessible to you.
In this example, the accessible population might be homeless males between the ages of 30 and 50 in six selected urban areas across the U. Or, you have to spell out in detail how you will contact them to assure representativeness. If you were doing a phone survey and selecting names from the telephone book, the book would be your sampling frame.
Notice that in this case, you might identify the area code and all three-digit prefixes within that area code and draw a sample simply by randomly dialing numbers cleverly known as random-digit-dialing. In this case, the sampling frame is not a list per se, but is rather a procedure that you follow as the actual basis for sampling.
Finally, you actually draw your sample using one of the many sampling procedures. The sample is the group of people who you select to be in your study. You may not be able to contact or recruit all of the people you actually sample, or some could drop out over the course of the study.
The problem of nonresponse and its effects on a study will be addressed when discussing "mortality" threats to internal validity. People often confuse what is meant by random selection with the idea of random assignment. You should make sure that you understand the distinction between random selection and random assignment.
At this point, you should appreciate that sampling is a difficult multi-step process and that there are lots of places you can go wrong. In fact, as we move from each step to the next in identifying a sample, there is the possibility of introducing systematic error or bias. For instance, even if you are able to identify perfectly the population of interest, you may not have access to all of them.
And even if you do, you may not have a complete and accurate enumeration or sampling frame from which to select. And, even if you do, you may not draw the sample correctly or accurately. And, even if you do, they may not all come and they may not all stay.
This is a very difficult business indeed.What Is a Sampling Frame? When developing a research study, one of the first things that you need to do is clarify all of the units (also referred to as cases) that you are interested in studying. Definition of the Sampling Frame and Sample 77 and Public Law (Persian Gulf War Veterans’ Health Status, Section , Expansion of Coverage of .
A sampling frame is a list or other device used to define a researcher's population of interest. The sampling frame defines a set of elements from which a researcher can select a . A set of information used to identify a sample population for statistical treatment.
A sampling frame includes a numerical identifier for each individual, plus other identifying information about characteristics of the individuals, to aid in analysis and allow for division into further frames for more in-depth analysis.
Populations: Definition - a complete set of elements (persons or objects) that possess some common characteristic defined by the sampling criteria established by the researcher Composed of two groups - target population & accessible population Target population (universe) The entire group of people or objects to which the researcher .
In statistics, a sampling frame is the source material or device from which a sample is drawn. It is a list of all those within a population who can be sampled, and may include individuals, households or institutions.. Importance of the sampling frame is stressed by Jessen and Salant and Dillman..
In many practical situations the frame is a matter of .