Page 72 - Global Project Management Handbook

THE FUTURE OF PROJECT MANAGEMENT 3-7

Metrics. The basis of a coword-analysis study is calculation of the equivalence or
link coefficient:

[E.ij] = ([C.ij]/[C.i]) × ([C.ij]/([C.j]) = [([C.ij]).2]/([C.i] × [C.j]) (1)
where [C.ij] is the co-occurrence frequency of the keyword pair ([M.i] and [M.j]) in the
set of articles, [C.i] is the occurrence frequency of keyword [M.i] in the set of articles,
[C.j] is the occurrence frequency of keyword [M.j] in the set of articles, and [E.ij] has a
value between 0 and 1.
This coefficient is used to define the clusters and draw the strategic diagram. A clus-
ter is a lexical structured set built from a co-occurrence analysis. It is constituted by a set
of words strongly associated or in strong co-occurrence in the documents. The co-
occurrence analysis is conducted through the index (list of words to take into considera-
tion) associated with the corpus of documents.

Density, Centrality, and Strategic Diagram. A strategic diagram is used to illustrate
the “local” and “global” contexts of themes. This diagram is created by putting the
strength of global context on the x axis (called centrality) and the strength of local
context on the y axis (called density). This diagram is used in many coword studies.
Two kinds of indexes (i.e., density and centrality) are used to measure the strengths of
local context and global context, respectively.
Density. Density is used to measure the strength of the links (equivalence or link
coefficient) that tie together the words making up the cluster. This is the internal strength
of a cluster and provides a good representation of the cluster’s capacity to maintain itself
and to develop over the course of time in the field under consideration (Callon et al.,
1991). Ranking subject areas (clusters) in terms of their internal coherence (density) is
designed to provide information for systematic discussion of a major policy alternative.
Further, sorting the keywords by decreasing order of density can provide a precise
description of the areas (Bauin et al., 1991). The value of the density of a given cluster
can be measured in several ways. Generally, the index value for links between each
word pair is calculated first. Then the density value can be the average value (mean) of
internal links (e.g., Turner et al., 1988; Coulter et al., 1998), the median value of internal
links (e.g., Courtial et al., 1993), or the sum of the squares of the value of internal links
(e.g., Bauin et al., 1991). An internal link means that both the words linked by it are

within the cluster. Here we consider the average value (mean) of internal links.
Centrality. Centrality is used to measure the strength of a subject area’s interac-
tion with other subject areas. Ranking subject areas (clusters) with respect to their
centrality shows the extent to which each area is central within a global network. The
greater the number and strength of a subject area’s connections with other subject
areas, the more central this subject area will be in the network (Bauin et al., 1991). For
a given cluster (area), its centrality can be the sum of all external link values (e.g.,
Turner et al., 1988; Courtial et al., 1993) or the square root of the sum of the squares
of all external link values (e.g., Coulter et al., 1998). More simply, it can be the mean
of the values of the first six external links (e.g., Callon et al., 1991). An external link
is one that goes from a word belonging to a cluster to a word external to the cluster.
Here we consider the mean of the values of the first six external links.
Strategic Diagram. A strategic diagram that offers a global representation of the
structure of any field or subfield can be created by plotting centrality and density into
a two-dimensional diagram (Law et al., 1988). Typically, the horizontal axis repre-
sents centrality, the vertical axis represents density, and the origin of the graph is at
the median of the respective axis values. This map locates each subject area within a
two-dimensional space divided into four quadrants. The strategic diagram is used in