Question

Sample Selection Methods. You are interested in selecting a sample of 100 students on your campus to participate in a survey of the effects of coffee on students’ ability to comprehend material from a faculty member’s lecture. You have decided to limit your selection to business majors and have obtained a comprehensive list (ranked in descending order based on grade point average) of all business majors. This list is 22 pages long and contains the names of 2,200 business majors. Required: a. When selecting your sample, what precautions should you take to ensure a representative sample? b. Briefly describe how you might select the sample using each of the following methods: (1) unrestricted random selection, (2) systematic random selection, (3) haphazard selection, and (4) block selection. c. What are some of the advantages and disadvantages of using the selection methods described in part (b)?

Answer 1

3 Features to Keep in Mind While Constructing a Sample

Consistency

It is important that researchers understand the population on a case-by-case basis and test the sample for consistency before going ahead with the survey. This is especially critical for surveys that track changes across time and space where we need to be confident that any change we see in our data reflects real change – across consistent and comparable samples.

Diversity

Ensuring diversity of the sample is a tall order, as reaching some portions of the population and convincing them to participate in the survey could be difficult. But to be truly representative of the population, a sample must be as diverse as the population itself and sensitive to the local differences that are unavoidable as we move across the population.

Transparency

There are several constraints that dictate the size and structure of the population. It is imperative that researchers discuss these limitations and maintain transparency about the procedures followed while selecting the sample so that the results of the survey are seen with the right perspective.

Now that we understand the necessity of choosing the right sample and have a vision of what an effective sample for your survey should be like, let’s explore the various methods of constructing a sample and understand the relative pros and cons of each of these approaches.

Random Sampling

When: There is a very large population and it is difficult to identify every member of the population.

How: The entire process of sampling is done in a single step with each subject selected independently of the other members of the population. The term random has a very precise meaning and you can’t just collect responses on the street and have a random sample.

Systematic Sampling

When: Your given population is logically homogenous.

How: In a systematic sample, after you decide the sample size, arrange the elements of the population in some order and select terms at regular intervals from the list.

Haphazard sampling is where you try to create a random sample by haphazardly choosing items in order to try and recreate true randomness. It doesn’t usually work, because of <a data-cke-saved-href="http://www.statisticshowto.com/what-is-bias/#SelectionB" href="http://www.statisticshowto.com/what-is-bias/#SelectionB" "="" style="border: 0px; font-family: &quot;PT Sans&quot;, sans-serif; margin: 0px; outline: 0px; padding: 0px; vertical-align: baseline; color: rgb(5, 169, 197); text-decoration-line: none;">selection bias: where you knowingly or unknowingly create unrepresentative samples.

Block selection is a type of judgment sample whereby accounts or items are chosen in a sequential order. Once the initial item in the block has been chosen, then the balance of theblock will be automatically selected.

Advantages of Sampling Method

1. Reduce Cost. It is cheaper to collect data from a part of the whole population and is economically in advance.
2. Greater Speed. Sampling gives more time to researcher for data collection, so it is quickly and has a lot of time for collection of inflammation.
3. Detailed Information. Investigator during studying a small universe provides a detail and comprehensive information’s.
4. Practical Method. Sampling is the only practical method when the population is infinite.
5. Much Easier. it is much easier to collect information from many individuals in a universe.

Disadvantages of Sampling Method

1. Careful sampling selection is difficult.
2. Experts are required for careful study of the universe.
3. If the information’s is required for each and every unit in the study, then it is difficult to interview each and every person in sampling method.