Section 9.2 reviews briefly the notion of shared leadership, followed by section 9.3 which elaborates
the topic of team effectiveness. Section 9.4 describes the method used to study the relationship
between vertical and shared leadership and team effectiveness. Drawing a distinction between vertical
leadership and shared leadership does not imply a value judgment on the superiority of one approach
over the other. Instead, what is needed is greater clarity on the appropriate level of analysis. When the
focal topic of study is leadership in teams, it is important to distinguish the level at which leadership is
conceptualized.
The sample used in this study is a subset of the sample used in the earlier presented confirmatory
study (chapter 7). This study described in this chapter starts by checking whether the factor structure
for the leadership dimensions is stable, given that the sample is different from chapter seven. Next, the
intraclass correlations and interrater agreements were calculated for each leadership dimension, before
aggregating to the level of the focal managers. In turn, the sample of focal managers was divided into
formal team leaders and team members, in order to be able to study shared leadership (the average of
the team members) as separate from vertical leadership (the formal team leader). A correlation matrix
was generated to unveil the interrelationships between the shared and vertical leadership dimensions.
A following step was calculating the team effectiveness scores. First, a confirmatory analysis was
conducted in order to confirm the factor structure (as the team effectiveness dimensions were drawn
from different previous studies and taken together for the first time), then the intraclass correlations
and interrater agreement were calculated before aggregating the scores given by the focal managers
themselves on team effectiveness into average team scores.
Lastly, section 9.6 presents a multiple regression analysis to gain insight into the absolute value of
both the vertical and shared leadership dimensions in terms of explaining the team effectiveness
scores. In order to test the relative value of shared leadership vis-à-vis vertical leadership, two
hierarchical regression analyses were conducted while employing a different order, first regressing
vertical leadership and then adding shared leadership and vice versa. On the basis thereof, one can
draw inferences as to whether shared or vertical leadership holds the largest explanatory value for the
respective team effectiveness scores.
9.2 SHARED LEADERSHIP
The topic of shared leadership has received a great deal of attention (Pearce & Conger, 2003a; Pearce
& Sims, 2002). Besides the notion of shared leadership, there are approaches emphasizing connective