DDBA 8300 Week 6 Sampling Logic Note Example

Twelve Who Have Done It Recently, Not Two Hundred Drawn at Random: A Sampling Logic Note for a Study of How City Procurement Managers Buy Cloud Software, Explaining the Number and the Roles Left Out

Student Name

Walden University

DDBA 8300: Qualitative and Quantitative Methodology for Applied Business Research

Instructor Name

Month Day, Year

Twelve Who Have Done It Recently, Not Two Hundred Drawn at Random: A Sampling Logic Note for a Study of How City Procurement Managers Buy Cloud Software, Explaining the Number and the Roles Left Out

The Question That Decides the Sample

My research question asks: "What strategies do procurement managers in mid-sized U.S. cities use to evaluate and contract for cloud-based software?" Cities with populations of 50,000 to 250,000 are moving functions such as permitting, utility billing and records management from software they own and run to software they rent online. Procurement rules written for buying equipment and services fit these contracts poorly, and managers have had to work out how to compare vendors, handle data security terms and price multiyear subscriptions. The question asks what managers do, which places the study in the qualitative tradition, and the sample must follow.

Two Ways to Sample

The first option is a random draw from a national directory. A professional association for public purchasing officials publishes a member directory listing about 2,800 procurement staff in cities of the target size. A random sample of 200, surveyed by questionnaire, would let me estimate how common certain practices are across mid-sized cities and generalize to the directory's population, within a margin of error.

The second option is a small purposeful sample: about twelve procurement managers who led at least one cloud software purchase worth more than $100,000 in the past three years, identified through public contract records and the association's discussion forums, and interviewed in depth.

Why Purposeful Sampling Fits

Patton (2015) describes purposeful sampling as choosing information-rich cases, people who can say a great deal about the issue at the center of the study. A random draw from the directory would include many staff who have never bought cloud software, or who bought it before current security standards applied, and who could say little about current strategies. The question asks how managers evaluate and contract, which only people who have recently done it can answer in depth. A random sample serves a different question: how common particular practices are.

Why About Twelve

Guest et al. (2006), coding sixty interviews in a study of a relatively uniform population, reported that by roughly the twelfth interview the coding had already captured nearly all the themes it would ever contain. Malterud et al. (2016) offered a broader principle, information power: the more relevant information each participant holds, the more focused the aim and the stronger the analysis, the fewer participants a study needs. My aim is narrow, participants are chosen because they hold exactly the experience the question asks about, and interviews will run about an hour each, which together point toward a modest number. I will begin with twelve and continue if later interviews still add new strategies, stopping when two consecutive interviews add nothing new.

Variation Within the Sample

Twelve managers chosen only for convenience might all come from one region or one kind of purchase. The sample will include managers from at least four regions, cities that bought from large national vendors and from smaller specialized ones, and at least two purchases that were later canceled or renegotiated, since failures may reveal strategies successes hide.

How Participants Will Be Found

Public contract records are the starting point. Most cities in the target range post council agendas and approved contracts online, and searching them for cloud subscriptions above $100,000 in the past three years should identify fifty or more purchases. The procurement officer named on each contract is the likely participant. The association's discussion forums will add managers whose purchases did not appear in searchable records. I will invite the first eligible manager from each region, then add others to fill the variation the next section describes, rather than inviting everyone at once and interviewing whoever answers first.

Roles Left Out, and Why

Three roles that touch cloud purchases are left out. Information technology directors, who often shape technical requirements, are excluded because the question concerns procurement strategies, and including them would broaden the study into technology selection. Vendors' sales staff are excluded because their perspective is commercial and would require a different protocol and consent arrangement. City council members, who approve large contracts, are excluded because they typically see a purchase only at the final vote. Each exclusion narrows what the study can say: it will describe procurement managers' strategies, not the whole decision. The limitations section will say so.

What the Choice Gives Up

The purposeful sample cannot say how common any strategy is among mid-sized cities. If the committee or a later study wants that, a survey of the directory would be the right next step, using the strategies identified here to write its items.

References

Guest, G., Bunce, A., & Johnson, L. (2006). How many interviews are enough? An experiment with data saturation and variability. Field Methods, 18(1), 59-82. https://doi.org/10.1177/1525822X05279903

Malterud, K., Siersma, V. D., & Guassora, A. D. (2016). Sample size in qualitative interview studies: Guided by information power. Qualitative Health Research, 26(13), 1753-1760. https://doi.org/10.1177/1049732315617444

Patton, M. Q. (2015). Qualitative research and evaluation methods (4th ed.). SAGE Publications.