Análisis de datos

A lot of attention has been focused by social network analysts on the subject of centrality in networks. Centrality, as a concept, is fundamental to the interpretation of social network data and originated in the work of Bavelas (1950) and Leavitt (1951) through their work at the Massachusetts Institute of Technology (MIT). The implication of centrality within a communication network has progressed through a number of phases of interpretative thought. Until the end of the 1970s the terms “centrality” and “power” were regarded as synonymous by many observers.

Brass and Burkhardt (1992:191) observed that most analysts would feel quite justified in declaring that the actor with the highest centrality (and this is often clearly evident from even a cursory glance at the relevant network diagram) to be the actor with the most power in the network.

These interpretations of the relationship between centrality and power were based upon the study of small groups of people in problem solving environments (see Mizruchi and Potts, 1998:354).

It is argued that this interpretative context serves this particular research project reasonably well^^. It is, however instructive to consider some o f the developments in this area of conceptual social network theory.

Much of the work that has been carried out in relation to centrality in networks

emphasizes the structural properties of human communication networks. It is

submitted that this is because human communication networks are the basis for social network theory; the use of the theory in the context of non-human networks is an application that must be justified and viewed in the context that the concepts were originally developed within.

To find a discussion of centrality relevant to this study, we need to turn to the work of Linton Freeman. Freeman’s seminal work on centrality in networks was written in the context of human communication networks and the application to this study is justified below. Freeman (1978:236) referred to three main groups of centrality measures: degree of points, betweenness and closeness. The degree of points (the extent to which a given point is connected to other points) provides a measure of communication activity (given that we are dealing with a communication network*^). High degree centrality implies the relative extent of the involvement of one actor in communications with the remainder of the group.

Betweenness (or frequency that a given point falls between any two other points) gives some measure of control over communication. Finally, closeness (involving the measuring of average lengths of paths for communications; short paths give few bridges) gives some measure of independence of an actor and efficiency of the organization (Freeman, 1978: 236).

This statement is made on the basis that much o f the activity within the construction project coalition involves small groups o f actors solving design problems, or problems associated with progress or financial constraints.

This research project deals with a specific type o f communication relating exclusively to project specific, information exchange activity. We are not dealing with other types o f communication here.

This research project is analyzing the relationship between project actors. Since these actors are firms for the purposes of producing contractual networks, the comparative analysis requires that we regard the project actors as firms for the

purposes of analyzing communication networks also. In order to create some

comparative data, and to limit the overall volume of data that was to be analyzed,

one definition of centrality needed to be selected. Inspection of the networks

presented in Freeman’s paper and comparison with the size and configuration of networks likely to be produced by our study of construction project coalitions indicated the following:

□ All three measures of centrality provided the same values for the best example of centrality (the star)

□ All three measures of centrality provide the same values for the least central scenario (an actor placed in a circle)

□ Degree-based measures provided the smallest range of variations in centrality values.

The choice of centrality measure was based upon an analysis o f the characteristics of these three measures (using Freeman’s paper of 1978) and their relevance to the research context and type of data produced.

At this point we have another conceptual bridge to cross; it relates to the relevance of the chosen measure of centrality (degree) to the analysis of networks relating to networks of contractual relationships.

The choice of degree centrality is rationalized above in a context of human communication networks. It also suggested that the centrality values generated by the construction project case studies would provide a measure o f power within the networks.

This was based upon the evidence of those who have correlated influence and power in small decision-making groups with communication network centrality. It is argued here, that although the concept o f power may be an issue (see the work of

Cox and Townsend 1998) it is not essential to this case study. We are seeking to

map changing patterns of influence within a given network; it is therefore proposed that the same formula for centrality be applied to all network calculations to provide a consistent and comparable measure of centrality across a number o f different types

of project network. It is, however, accepted that the justification of centrality

measure was based upon criteria that related to communication networks alone. It is suggested that those who have referred to the importance of power in procurement

routes, might be persuaded that it is in fact centrality (as distinct from power) that is

important for the reasons given above.

High centrality in a given network is no guarantee of success in terms of exercising control over events and the activities of other actors. Mizruchi & Potts (1998:384) contend that the extent to which centrality affects power in a given network is dependent on the structure of the network as a whole; the number and structure of subgroups and the extent to which the central actor can influence these sub-groups is also important.

Centrality, then, is an important measure for this research project. Centrality

(related to prominence in item 3 above, under the heading of “Five basic

premises..”) will be used to analyze the prominence o f the main project actors*^ and, in particular, the effects on these actors of the new initiatives in procurement and management. This aspect of an actor’s position in a network is referred to above as “prominence” *^.

For example, client, contractor architect, structural engineer etc

This leaves us with a number o f problems. Wasserman and Faust (1997:169) refer to “importance” and “prominence” as synonymous. Point centrality (and we probably need not concern ourselves with the local/global issue here) is regarded by Wassermann and Faust as a measure o f prominence or status within network, providing that the data is directional. The work o f Freeman in this area is most important; see for example. Freeman, LC (1979) “Centrality in Social Networks: 1. Conceptual Clarification” in Social Networks 1, 215-29

Comparisons can be made within the project and with other comparative projects. Hence, we are able to give a mathematical value to the centrality of the architect in the contractual, performance incentive and information exchange networks within a given project. The differences in these figures, for a given project, highlight what I shall refer

to as a lack of correspondence in forms of governance within the project coalition^®.

By comparing case studies at the level of one specific type of network^ % we are able to quantify the relative importance of each form of governance over a number of projects and therefore map the changes that reforms in procurement and management techniques have created.