Introduction into case study research

Transcription

1 Introduction into case study research Proseminar Foundations in Empirical Software Engineering Christos Tsakiroglou Institut für Informatik Software & Systems Engineering

2 Outline 1. What is a case study? 2. Why case studies in software engineering? 3. Main structure of the case study process Introduction into case study research 2

3 1. What is a Case Study? Case study refers to the collection and presentation of detailed information about a particular participant or small group. Case studies are analyses of persons, events, projects or systems that are studied holistically by one or more methods. The case that is the subject of the investigation will be an instance of a class of phenomena that provides an analytical frame (an object) within which the study is conducted and which the case illuminates and explicates. G. Thomas Introduction into case study research 3

4 1.1 Research Based Classification There are four types of purposes for research classification (Robson): Exploratory most of the case studies Descriptive Explanatory Improving Introduction into case study research 4

5 2. Why Case Studies in Software Engineering? commonly used areas: Psychology sociology social work business community planning Software development is carried out by individuals, groups and organizations social and political questions are of importance for this development. Software engineering is a multidisciplinary area Introduction into case study research 5

6 2. Why Case Studies in Software Engineering? (2) Benefits of Case Studies Find on what to focus. Flexible design. Gain more detailed and rich data Very responsive to local situations, conditions, and stakeholders needs Introduction into case study research 6

7 3. Main structure of the case study process Introduction into case study research 7

8 3.1 Case Study Design and Planning Introduction into case study research 8

9 3.1.a Types of Case Study Positivist evidence for formal propositions, measures variables, tests hypotheses draws inferences explanatory category (Robson) Interpretive understand phenomena from interpretation of their context Critical being emancipatory in order to improve the investigated case (Improving case studies) Intrinsic genuine interest, intent is to better understand the case, purpose is NOT to build theory Instrumental insight into an issue, helps to refine a theory, the case is of secondary interest Introduction into case study research 9

10 3.1.b Case Study Planning A plan for a case study should at least contain the following elements (Robson): Objective what to achieve? The case what is studied? Theory frame of reference Research questions what to know? Methods how to collect data? Selection strategy where to seek data? Introduction into case study research 10

11 3.1.c Case Study Designs A Single case can be either holistic or embedded (Yin) Holistic: whole case Embedded: multiple units of analysis Introduction into case study research 11

12 3.1.d Case Study Protocol Case Study Protocol is a set of comprehensive guidelines. Contains procedures for conducting the research, the research instrument guidelines for data analysis. A protocol is kept for the following reasons: guide when conducting the data collection makes the research concrete in the planning phase. review from third- parties in order to give feedback. can serve as a log of data collection Introduction into case study research 12

13 3.2 Collecting Data Introduction into case study research 13

14 3.2 Collecting Data (2) Methods for collecting data: Interviews: unstructured, semi-structured and fully structured Observations: monitor a group of people and then analyze it through protocol analysis Archival data: documents from different development phases, organizational charts, financial records etc. Metrics: for quantitative data collection Introduction into case study research 14

15 3.3 Analyze Data Introduction into case study research 15

16 3.3 Qualitative Data Analysis Basic objective of the analysis is to derive conclusions from the data, keeping a clear chain of evidence. Chain of Evidence means that a reader should be able to follow the derivation of results and conclusions from the collected data. In addition for achieving an effective data analysis: analysis and data collection should be done in parallel use of systematic analysis techniques General Techniques for Analysis: Hypothesis generation is intended to find hypotheses from the data Hypothesis confirmation are used to confirm that a hypothesis is really true Introduction into case study research 16

17 3.4 Validation of Case Studies The validity of a study denotes the trustworthiness of the results, to what extent the results are true and not biased by the researchers subjective point of view. There are many classification schemes for validity. Yin Construct validity, Internal validity, External validity, Reliability Robson Yin s classification scheme is probably the most suitable for case studies. used in controlled experiments in software engineering Introduction into case study research 17

18 3.4 Aspects of Validity When the researcher and the interviewed persons do not interpret the interview questions in the same way (Construct validity) When an unknown by the researcher factor affects the investigated causal relation (Internal validity) To what extend is it possible to generalize the findings in order to extend them in cases and define a theory. (External validity) to what extend the data and the analysis are dependent to the specific researcher (bias, Uncertainty). (Reliability) Introduction into case study research 18

19 3.4 Consider Validity Important is to consider the validity of the case study from the beginning. Possible ways to improve validity are triangulation, case study protocol and its review Introduction into case study research 19

20 3.4.a Triangulation Denzin identified four types of triangulation: Data source triangulation: when different sources of information are involved in order to increase the validity of a study. Investigator triangulation: when several investigators examine the same phenomenon; Theory triangulation: when investigators with different view points interpret the same results; and Methodological triangulation: when one approach is followed by another, to increase confidence in the interpretation Introduction into case study research 20

21 3.5 Reporting Introduction into case study research 21

22 Reporting The report communicates the findings of the study. It is also the main source of information for judging the quality of the study. Robson defines a set of characteristics which a case study report should have which in summary implies that it should: tell what the study was about communicate a clear sense of the studied case provide a history of the inquiry so the reader can see what was done, by whom and how. provide basic data in focused form, so the reader can make sure that the conclusions are reasonable articulate the researcher s conclusions and set them into a context they affect Introduction into case study research 22

23 Reporting Structures Alternative structures for reporting case studies in general (Yin): Linear-analytic: the standard research report structure (problem, related work, methods, analysis, conclusions) used in academic case studies Comparative: the same case is repeated twice or more to compare alternative descriptions, explanations or points of view. Chronological: a structure most suitable for longitudinal studies. Theory-building: presents the case according to some theory-building logic in order to constitute a chain of evidence for a theory. Suspense: reverts the linear-analytic structure and reports conclusions first and then backs them up with evidence. Unsequenced: with none of the above, e.g. when reporting general characteristics of a set of cases Introduction into case study research 23

24 Recap Case Studies 1. What is a case study? 2. Why case studies in software engineering? 3. Main structure of the case study process Introduction into case study research 24

25 Thank you very much for your attention! Questions?? Introduction into case study research 25

26 Main References Case Study Research: Design and Methods, Robert K. Yin, SAGE 2009 Guidelines for conducting and reporting case study research in software engineering. Per Runeson, Martin Höst Application of a Case Study Methodology by Winston Tellis Introduction into case study research 26