4. Introduction
4.3 Research Methodology
4.3.2 Sampling
Sampling is the process of selecting target participants that represent a research population, in order to obtain information about the whole research population by examining only a part of it (Babbie & Mouton, 2001; Mlitwa, 2011). In order to simplify the process, the research population can be divided into manageable groups and the study can be conducted on each group.
Sampling has two categories: probability and non-probability. Probability sampling refers to a process where the numbers and location of the elements of a research population is known to, and is reachable by a researcher, where all elements of a research population have an equal chance of being selected or excluded from a research sample. Probability sampling can be further divided into three types namely: simple random sampling, Stratified sampling and cluster sampling (Barbie & Mouton, 2001).The current study operates over a broad spectrum where it was impossible to access the entire research population since it is sparsely populated around the world. This makes it impossible to count all the numbers and know the entire target research population. Therefore probability sampling is inappropriate for this study. Thus, non-probability sampling techniques need to be used for this kind of study.
4.3.2.1 Non-Probability Sampling
Non-probability sampling refers to the process where elements of a research population are selected by non-random methods. It is often used when the number of elements in a research population is unknown and their locations are difficult to identify (Kitchenfham & Pfleeger, 2002).
The research population in the current study falls under this description. For example, the Scrum software development teams are numerous and too widely spread for their complete number and location to be known with full certainty by the researcher. Without certainty on the number and location of all Scrum development teams, it was impractical for a researcher to randomly select a representative sample from a research population of software development teams operating in Scrum projects.
There are many types of non-probability sampling techniques, with each type determined by the nature and objective of the study, the research problem and the type of a research population
58 under investigation. The three most common non-probability sampling techniques are quota sampling, snowball and purposive sampling.
Quota sampling is a type of nonprobability sampling which describes the research population characteristics (Babbie & Mouton, 2001). Quota sampling is appropriate for studies where there is no list of the research population being studied. Snowball sampling refers to the process of identifying a research population using a network by starting with few participants in a group (Neuman, 2006). In this approach data is collected from a few participants who can be identified and the identified participants are asked to help in locating other participants (Kitchenham & Pfleeger, 2002). Snowball sampling is appropriate for studies where the research population is difficult to locate and identify (Babbie & Mouton, 2001). For example, doing a study of people who live on the street where it is rare to find a participant in one particular location (ibid). This method is often used for hidden research populations which are hard to access. In contrast, the target research population for this study operates over a broad spectrum, therefore snowball sampling is inappropriate. Instead, purposive sampling is employed.
4.3.2.2 Purposive Sampling
Purposive (or judgmental) sampling is a non-random sampling technique that uses various ways to locate possible cases in a situation where participants are difficult to locate (Neuman, 2006).
It is often used when the researcher wants to describe a phenomenon about which little is known, or when it is impossible to gather elements by random selection from a list, into the sample (Mchunu, 2013). In this technique, participants were identified and selected according to their direct relevance to the purpose of the study, using the judgment and the discretion of the researcher (Mlitwa, 2011). The research population in the current study fits this description, which makes purposive sampling the most appropriate technique for the identification and selection of Scrum teams for direct and indirect observation, and of the associated individual participants for interviews.
The application of the purposive sampling technique in this study is outlined in Table 3 and elaborated in detail in the sections that follow.
59 Table 3: Sample Selection
Research Question: How can software quality assurance (SQA) processes be understood and applied to maximize the quality of software in Scrum projects?
Theme of Investigation
Data Source Tools Unit of Analysis Unit of Observation No. of
Participants Background,
methodology, &
theoretical basis.
Literature Read, analyse, write Books, articles, papers Research methodology books, Software Development (SD) journal articles &
conference papers.
SQA processes in Scrum projects
Literature
Experts
Read, analyse, write
Interview
Books, articles, papers
Academics & Industry experts
SD journal articles & conference papers.
Academics (2 x from NMMU); and
Experienced practitioners in SD: Team lead, Scrum Master (1 x EOHMC; 1 x Old Mutual; 1 x Truworths; 1 x Saratoga; 1 x ScrumSense).
2 academics 7 Practitioners Significance of SQA in
Scrum projects
Literature
Experts
Practitioners
Read
Interview
Interview
& observations
Books, articles, papers
Academics & Industry experts
Scrum team leaders &
Scrum teams
SD journal articles & conference papers.
Academics (2 x from NMMU); Experienced practitioners in SD: Team lead, Scrum Master (1 x EOHMC; 1 x Old Mutual; 1 x Truworths;
1 x Saratoga; 1 x ScrumSense).
SQA awareness among Scrum teams
Practitioners Interview &
observations
Scrum team leaders &
Scrum teams Team lead, Scrum master (1 x EOHMC; 1 x Old Mutual; 1 x Truworths; 1 x Saratoga; 1 x ScrumSense).
SQA practices in Scrum projects
Projects success rate in Scrum projects
Explanations to current success/failure rate
60 In an attempt to realize the objectives of this investigation, the research question was split into five main issues/themes of investigation.
The first of these themes (issues of investigation) pertains to ascertaining the exact software quality assurance (SQA) processes that exist in Scrum software development methods. Insight on this theme is considered a basis upon which the rest of the questions can be built. Software development (SD) books, journals and conference papers, as well as insight from experienced academics and industry experts were used as data sources to answer questions under this theme.
For this theme in particular, two participants were chosen: two academics, one of whom is an experienced researcher and a lecturer, with many years of practical industry experience. They were selected from the departments of information technology and computer science at the Nelson Mandela Metropolitan University (NMMU). On the basis of their direct academic expertise and practical experience in agile methods and related software issues, they were considered to be the most relevant sources of data for this theme. The university department was chosen purely on the basis of convenience to the researcher. The researcher is familiar with the institution and using academics in these two departments simplified access to data sources.
For obtaining answers for all themes, ten industry practitioners were chosen from the participating companies. The participating companies are EOH Microsoft Coastal (EOHMC), Old Mutual South Africa, ScrumSense, Saratoga and Truworths.
The group of industry practitioners consisted of a Scrum-team, team leader and a Scrum- master, from each of the Scrum teams, across the five participating software development companies in South Africa. Participating companies in this respect are EOH Microsoft Coastal (EOHMC), Old Mutual South Africa, ScrumSense, Saratoga and Truworths. They were selected on the basis of their common use of Scrum methods in their projects as well as their easy accessibility to the researcher. Each team leader and a Scrum master are directly involved with all aspects of Scrum processes. This includes planning and supervising projects, implementing SQA standards and ensuring that a quality product is delivered to the customer.
The second theme/issue of investigation, the significance of SQA processes, focuses on assessing the importance of SQA, for example, whether it is considered to be a really necessary part of the Scrum software development processes.
61 Building on this theme, the third issue of investigation – SQA awareness, is directed at exploring whether (and to what extent) SQA is known among Scrum teams.
The SQA practices in the fourth theme focusses on understanding the patterns which emerge about how SQA is (or is not) being implemented in Scrum teams.
Irrespective of the status of SQA implementation, the fifth theme is designed to explore the success rate of Scrum projects, with inferences related to quality assurance practices.
Questions pertaining to explanations of the status quo are captured under the sixth theme – explanations referring to the success/ failure rate of Scrum projects in each of the five teams.
The sources of data to the rest of the five themes are the team-leaders and Scrum-masters from each of the Scrum teams at EOH Microsoft Coastal (EOHMC), ScrumSense, Old Mutual South Africa, Saratoga and Truworths companies in Cape Town, selected for similar reasons as outlined under the first theme.
Qualitative analytical methods were then used to analyse the data obtained from these themes of focus.