Population and Sample

Once the research methodology and design has been determined, the next step is defining the correct population and sample size. As with all research a good sample must be representative, accurate, precise, and large enough to be reliable. This module looks in detail at what makes a good sample and how to choose a sampling strategy. Additionally, this module discusses how to select an appropriate site partner for the research study.

Learning Objectives

• Understand the difference between population and sample and the importance of each
• Understand how to define your study sample
• Be able to explain the basics of various sample strategies
• Know how to select a site partner for your study

Population

Determining the population and sample size begins with reviewing the research methodology and design in order to accurately define the correct approach. As such, a study using a qualitative methodology includes a much different population and sample size than that of a quantitative research project. The population is the overall group of people affected by the research project. 

Sample

Similar to defining the population, the appropriate sample size is also determined by the research methodology. Morse (2000) stated that the scope of the study, nature of the topic, quality of the data, and study design determines the appropriate sample size. Therefore, the research methodology needs to be determined before a population or sample is selected. 

Qualitative sampling comes in a variety of forms and the use of each is dependent on the population and researcher’s access to the intended population. Purposive sampling occurs when the researcher chosen the sample in a deliberate manner by selecting those that will yield relevant data (Yin, 2016). Another technique used in qualitative research is snowball sampling. Thompson (2002) stated snowball sampling occurs when one participant identifies additional possible participants who fit the criteria for the research study. Convenience sampling is used when a researcher selects participants simply because they are readily available. However, convenience sampling may provide an unwanted degree of bias so this technique should be used sparingly and with caution (Yin, 2016).  

Quantitative research requires the sample size be large enough to produce statistically significant results. For large-scale quantitative studies, it is appropriate to contact a much larger number of people than a small, qualitative study. According to Dawson (2019) many researchers believe for quantitative studies, the larger the sample population then the more accurate the results. However, researchers need to take into consideration the amount of time and financial resources it would take to include such many participants. For quantitative projects, the use of statistical methods are often used to determine the required sample size to meet validity and reliability standards.

Consult the Research Ready certifications on qualitative and quantitative sampling techniques for more information.

Site Partner

Finding a site partner is a crucial consideration at this early stage because the process can take time. The first step is finding a business that is willing to give access to their data and their employees without trying to influence the findings of the study. The company you work for or have connections to may seem an obvious partner, but as seen in the findings of Wallace and Sheldon (2015) the close relationship between researcher and participants can present its own ethical challenges. 

Ideally, the researcher’s relationship with his/her site partner should be open, trusting, and built upon mutual respect. This should extend beyond the site partner company principals to include actual study participants and all interested parties (Zikmund et al., 2013).  

Of particular concern in business research is the risk that study results could be used for internal political purposes if they support a manager’s position. On the other hand, there could be an attempt to block dissemination of the findings if they are unfavorable to the site partner. Basic considerations of ethics and fairness between researcher and the site partner, together with the strength of their open trusting relationship, will help the researcher to avoid such difficult situations (Zikmund et al., 2013). 

Scenario: ABC Consulting

For the ABC Consulting example, the general population will be the entire company workforce. The sample would depend on the method and design used. It may include a large number (such as 100) of analysts for a quantitative study. In a qualitative study, it may only refer to a small number (5-6) sales directors. The sample will greatly depend on the method and design being employed. For this study, a survey was sent to an entire department of 200 members seeking their input. A focus group of five sales directors was conducted.

For Further Study

Sampling: Simple Random, Convenience, Systematic, Cluster, Stratified: https://youtu.be/be9e-Q-jC-0

Techniques for Random Sampling and Avoiding Bias: https://youtu.be/PdXDLNNXPik

Type of Sampling Methods: https://youtu.be/pTuj57uXWlk

Simple Random Sampling: https://youtu.be/yx5KZi5QArQ

Convenience Sampling: https://youtu.be/MJjq0NILrnk

Systematic Sampling: https://youtu.be/QFoisfSZs8I

Cluster Sampling: https://youtu.be/QOxXy-I6ogs

Stratified Sampling: https://youtu.be/sYRUYJYOpG0

How to Calculate Sample Size: https://youtu.be/Z2dKK1xicgs

G Power Sample Size Calculator: http://www.gpower.hhu.de/

References   

Dawson, C. (2019). Introduction to Research Methods 5th Edition: A Practical Guide for Anyone Undertaking a Research Project. Robinson.

Kothari, C. R. (2004). Research methodology: Methods and techniques: New Age International.

Morse, J. M. (2000). Determining sample size. Qualitative Health Research, 10(1), 3-5. DOI: 10.1177/104973200129118183

Wallace, M., & Sheldon, N. (2015). Business research ethics: Participant observer perspectives. Journal of Business Ethics, 128(2), 267-277.

Yin, R. (2 Eds.). (2016). Qualitative research from start to finish (2^nd ed.). New York, NY: The Guilford Press. 

Zikmund, W. G., Babin, B. J., Carr, J. C., & Griffin, M. (2013). Business research methods: Cengage Learning.