Validity and reliability 39 

When assessing the employed methodologies, reliability and validity are two important criteria. Reliability can be defined as the possibility to replicate the study. Given that several of the conducted case studies are based upon historical events which have been described through both accessing key interviewees and internal documents, it should be possible to replicate these studies. This kind of formal documentation is often considered to be stable, unobtrusive and exact (Yin, 1994). It can be reviewed by another person who would most likely draw similar conclusions. The reliability of the three studies which do not rely upon archival sources is admittedly weaker. However, the documentations and explanations of the explained methods above should still make it possible to repeat the studies.

Validity can be thought of as either internal or external. Internal validity refers to how well the collected data match the reality that they seek to represent. There are several ways to improve the internal validity. One way of doing so is to use different sources of data and then triangulate (Yin, 1994). In the abovementioned studies, the internal validity was enhanced by using several different sources such as interviews and access to a vast amount of archival data. Since the case studies emerged from similarities in those different sources and were often subsequently confirmed by conducting follow-up interviews, the internal validity could be increased. Another way of improving it is to compare data with existing literature (Eisenhardt, 1989). Such comparisons and contrasts have to some extent been made in the articles that emerged from the different studies.

Interviews are subject to selection and respondent bias, as these data by necessity mirror an individual’s beliefs, values and experiences (Flick, 2006). As was stated in the descriptions above, this issue has been handled by interacting with the respondents throughout the studies. Key respondents have been asked to proofread and comment on case descriptions and moreover, the follow-up sessions, seminars, workshops and company presentations that have been held have contributed to ensuring a correct documentation. Furthermore, interviews have often been recorded and transcribed and in many cases performed together with another person, which also contributed to increasing the reliability of the studies.

A couple of other measures have been taken throughout the course of this research in order to offset the abovementioned problems. It is important to make sure that the interviewee can express opinions without being subject to undesired repercussions. When required, the author has therefore on several occasions signed Non-Disclosure Agreements. However, as the presented work is more concerned with innovation processes and networks than with innovation content, this was often not necessary. In those cases when an interviewee wished to be anonymous this was also arranged.

While this dissertation addresses the role of value networks and business models with regard to disruptive innovation, it has primarily relied upon sources from focal firms rather than their surrounding networks. There are several reasons why this approach has been employed.

Firstly, the thesis is primarily concerned with the challenges that these firms encounter, how they introduce disruptive innovations and try to change their business models. Secondly, while the firm’s environment is of great interest, it can still be studied and understood by approaching the firm. After all, the focal firm is the one actor that is subject to the external control and is the one that encounters the difficulties which need to be studied with regard to disruptive innovation. As the conducted research is concerned with the challenges a firm encounters and how the innovations emerge, the focal firm is arguably the actor that it is most suitable to address. Thirdly, it would be interesting to study a network in its entirety, but such an approach is by necessity more time consuming and would thus have drawn upon fewer, more detailed studies which in turn would have resulted in a reduced generalizability. Within the scope of this doctoral research project it has therefore not been possible to collect data from entire networks.

The external validity can be defined as the possibility to draw general conclusions from the conducted research. It is often argued that case studies impose constraints upon the external validity of the findings, given the explicit focus on a certain event (Yin, 1994). It should be pointed out here that the presented work aims to develop new theory rather than testing existing theory. According to Eisenhardt (1989) a case study is the appropriate research strategy when little is known about a phenomenon and existing theories seem inadequate or insufficient. This dissertation does not aim to provide an exhaustive set of answers. The purpose is rather to improve existing theory related to disruptive innovation.

The potential weakness in terms of external validity has been handled in a couple of different ways. Some generalizations can be made by carefully choosing which cases to investigate. An attempt to do so is made in the first study and the resulting paper about Hasselblad and the shift to digital imaging. The second appended article draws upon this study of one firm in the camera industry, and then discusses on a more general level whether this pattern is applicable to other industries where microelectronics has displaced other technologies. While such generalizations are partly speculative, they may still inform the reader and trigger further research into the same area.

The external validity can be increased analytically, i.e. by relating cases to theory and thereby reaching conclusions which are more general. The cases have helped to illustrate and point out issues which need to be better understood theoretically. Such an empirically informed perspective can hopefully in turn result in conclusions which are still valid. The fourth appended article and this covering paper focus explicitly on doing so. These documents seek to develop theory by synthesizing theory and the observations that have been made in other articles and studies.

The fact that some studies draw on a wider set of cases should hopefully also result in a higher external validity since they can be compared and contrasted to each other. In this dissertation the studies and corresponding papers differ in terms of how detailed the cases

are. Some of the articles are written with a high level of detail whereas other studies draw upon a wider range of cases. The articles which draw upon a wider sample should hopefully result in a broader and more comprehensive understanding of the studied questions.