unlearned (Faerman & Peters, 1991). Moreover, by increasing the understanding of similarities and
differences, higher-level managers will be less inclined to have performance expectations of their
subordinates based on judgments regarding how managers at their own level of the hierarchy should
be performing (DeChurch et al., 2010).
10.4 LIMITATIONS AND SUGGESTIONS FOR FURTHER RESEARCH.......................................................................................
This dissertation holds promising value, yet several limitations can be identified which open up the
opportunity for additional studies. First of all, other researchers are encouraged to validate and retest
the strategic leadership model as conceptualized and operationalized in this dissertation. The
availability of a valid and reliable instruments allows for testing in different samples and across
different industries. But also in terms of test-retesting. How stable are the behaviors across individuals
and teams?
Moreover, the findings concerning middle managers require further attention. The societal trends of
delayering and horizontal organizations, put a stress on the role of middle managers. Many firms have
reduced the number of managerial layers (Littler et al., 2003; Powell, 2002). Especially the normative
claim that these managers need to play both a strategic and supervisory leadership role may lead to
particular role stress. There is relatively little attention in the leadership literature for the changing role
of middle managers. The findings of this research unveil that middle managers should be treated as a
distinct category. The strategic leadership concept seems useful to this extent, but should be extended
further with a larger sample of middle managers.
The sample size for measuring the impact of shared and vertical leadership on team effectiveness was
small (even though hundreds of individuals filled in the measurement instrument ± the aggregations
led to a sample size of N=30). Additional data at the team level would facilitate the specification of
more complex causal models. Thus, future research would do well to collect larger data sets
(including more teams). The findings of this research strongly support an important role for shared
leadership in explaining team effectiveness. Given the increasing importance of teams in
contemporary organizations, further research is definitely required, to demonstrate the value the
alternative source of leadership in alternate organizational contexts.