Population
The study wants to use the librarians and the library users of the Clayton County Public Library System as the population of the study. Johnston and Sabin (2010) advise researchers to obtain the study population from the appropriate target population to enhance the generalizability of the findings. The study population should reflect the target population for the findings to have empirical application. In this view, the study population in Clayton County Library System should be similar to the target population in both private and public libraries. Thus, the librarians are the appropriate population of the study because they understand the quality of services that they provide. Given that the librarians understand the management of libraries and the nature of the services that they offer, they form an important population for the study of the financial sustainability of the Clayton County Public Library System. According to Daugherty and Russo (2013), librarians play a central role in the management of the library and consequently determine its sustainability. As the study assumes that financial sustainability is dependent on sources of funds, the librarians are in a position to explain the financial sustainability of various sources of funds that the library relies on in providing services to its customers.
Moreover, the library users form an important population of study because they understand the quality of services that they receive from the library. The perceptions of library users provide the best way of gauging the quality of services that libraries provide to the public (Cook & Heath, 2001). In this view, the library users provide invaluable views that can enable researchers to predict the sustainability of the Clayton County Public Library System relative to its sources of funds. The extent of user satisfaction predicts the quality of services that a library offers and consequently shows its financial stability and sustainability over a certain period (Andaleeb & Simmonds, 1998). Therefore, library users comprise a critical population of the study, as they can assess the quality of services, and thus allow researchers to infer the financial sustainability of the library.
The Clayton County Public Library System comprises six branches of the library, which implies that the study obtains the study population from the six branches. The six branches are Headquarters branch, Forest Park branch, Jonesboro branch, Lovejoy branch, Riverdale branch, and Morrow branch. Given that the study targets the staff (librarians) and library users, it estimates that the Clayton County Public Library System has about 50 librarians and approximately 3,000 users. Statistics show that the library has approximately 0.5 million books, 10, 000 audiotapes, 5,000 videocassettes, and 500 subscribers of journals, magazines, and newspapers while serving about 1.3 million visitors per year (Clayton County Public Library System, 2014). Hence, the library serves a huge number of users in Clayton County and other regions. With the advent of digitization of resources, the library has tremendously increased its users. Digitization enhances the accessibility of resources and the quality of access (DeGRacia, 2009; Erway, 2012). Hence, the population of library users in the Clayton County Library System is increasing with time.
Sampling
The study will derive the sample of the study from the study population, which comprises of the librarians and the library users. According to Punch (2005), since it is impractical and impossible to study the target population, sampling is necessary. Sampling is the process of selecting a portion of the target population for purposes of study. Brunt (2001) asserts that sampling aims at selecting a section of the population that represents the entire population for the findings to gain external validity. In this view, sampling of the librarians and the library users should ensure that the sample is representative of the target population. Frankfort-Nachmias and Nachmias (2008) affirm that sampling is important because it determines the generalizability of the findings. Therefore, the study will use a probability sampling design to ensure that the librarians and the library users have an equal chance of participating in the study and thus guarantee the representativeness of the study sample.
In sampling, the study will specifically apply a simple random sampling method, which is a probability sampling design. Jawale (2012) argues that simple random sampling gives individuals in the target population an equal chance of participation, and thus ensures representation of the population. Normally, sampling is prone to selection biases that researchers apply in the selection of participants, which is a great challenge that reduces generalizability of the findings. Essentially, probability sampling and random sampling apply randomization as a strategy to overcome the selection biases, which normally influence the effective representation of the target and the study population. According to Bull (2005), simple random sampling is advantageous because it is free from systemic error, which is common in other sampling methods. Simple random sampling maximizes external validity because it allows researchers to make inferences about the target population (Dattalo, 2010). Given that the objective of sampling is to select a study population that reflects the target population, randomization enhances the representation of the target population. Hence, simple random sampling is a suitable method for the study because it reduces selection biases and enhances the representation of the target population.
The procedure of applying simple random sampling in the selection of study participants should give each participant an equal chance of participation. In selecting the librarians, the study will list the number of librarians and assign them different numbers that range from 1 to 50. The numbers of 1 to 50 represent the number of librarians that are present in the Clayton County Public Library system. Simple random sampling requires a list of the study population to ease the selection of participants (Brunt, 2001). In this view, the study will write the numbers of the librarians and put them in a box. The next step is to mix and draw out a specific number of slips. The numbers that appear in the slips will be the participants of the study. Likewise, regarding the library users, the study will write slips that have yes or no labels, and then allow the library users to pick from a box. The users who select slips with a yes will qualify to be participants of the study.
In determining sample size, the study will consider statistical power, alpha, and effect size, which are three elements that influence the size of a sample in a given study. Lenth (2010) states that the statistical power of 0.8 and the alpha level of 0.05 are appropriate in determining sample size because they reduce the chance of making systemic errors. Thus, the study will use the statistical power of 0.8 and the alpha value of 0.05 in determining the sample size. Owing to the complexity of calculating effect size, Cohen suggests that the values of the small, medium and large effect sizes are 0.2, 0.5, and 0.8 respectively (Huberty, 2002). Since the population of librarians is approximately 50, the study will use 0.7 as the value of effect size. Comparatively, given that the population of the library users is about 3,000, the study will take 0.2 as the value of effect size. Therefore, from the t-test table, the sample population of the librarians is 19, while the sample population of the library users is 394 (Dattalo, 2007). Thus, the sample size is enough to enhance the external validity of the findings.
References
Andaleeb, S., & Simmonds, P. (1998). Explaining user satisfaction with academic libraries. College & Research Libraries, 59(2), 156-167.
Brunt, L. (2001). The advent of the sample survey in the social sciences. Journal of the Royal Statistical Society, 50(2), 179-189.
Bull, B. (2005). Exemplar sampling: Nonrandom methods of selecting a sample which characterizes a finite multivariate population. The American Statistician, 59(2), 166-172.
Clayton County Public Library System (2014). Quick Facts: 2010-2011 Fiscal Year Statistics. Web.
Cook, C., & Heath, F. (2001). User’s perceptions of library services quality: A LibQUAL+ qualitative study. Library Trends, 48(4), 548-584.
Daugherty, A., & Russo, M. (2013). Embedded librarianship: what every academic librarian should know. London: ABC-CLIO.
Dattalo, P. (2007). Determining Sample Size: Balancing Power, Precision, and Practicality: Balancing Power, Precision, and Practicality. New York: Oxford University Press.
Dattalo, P. (2010). Ethical dilemmas in sampling. Journal of Social Work Values and Ethics, 7(1), 1-23.
DeGRacia, J. (2009). The digitization decision: Factors to consider when converting material to digital format. Library Student Journal, 1(1), 1-16.
Erway, R. (2012). Increasing Access to Special Collections. The Journal of the Association of European Research Libraries, 21(2), 1-9.
Frankfort-Nachmias, C., & Nachmias, D. (2008). Research methods in the social sciences (7th ed.). New York: Worth.
Huberty, C. J. (2002). A history of effect size indices. Educational and Psychological Measurement, 6(1), 227-240.
Jawale, K. (2012). Methods of sampling design in the legal research: Advantages and disadvantages. Online International Interdisciplinary Research Journal, 2(6), 182-190.
Johnston, L., & Sabin, K. (2010). Sampling hard-to-reach populations with respondent driven sampling. Methodological Innovations Online, 59(2), 38-48.
Lenth, R. (2010). Some Practical Guidelines for Effective Samples Size Determination. The American Statistician, 55(3), 187-193.
Punch, K. (2005). Introduction to Social Research: Quantitative and Qualitative Approaches. London: SAGE Publisher.