the eVect of one activity is actually contingent on the other activities present. These
eVects can be further distinguished into three separate categories.Substitutable
eVectsoccur if the HRM activities are substitutes for each other in that each activity
results in an identical outcome (e.g. two diVerent personality tests that assess the
Big Five personality traits in the staYng area). Having two activities that are
substitutes results in outcomes equal to one practice alone. Thus, nothing is gained
from an organizational eVectiveness perspective. In fact,Wnancial performance
eventually decreases due to the additional costs of having two HRM activities that
yield identical outcomes.
The most interesting synergistic eVects, and the ones most commonly associated
with the internalWt perspective of SHRM, are ‘powerful connections’ and ‘deadly
combinations’ (Becker et al. 1997 ). They get to the core ofWt, alignment, and
synergy in that it is proposed that complementary HRM activities have greater
eVects on organizational eVectiveness than the sum of the eVects of each individual
activity (Ichniowski et al. 1997 ).Positive synergistic eVects(‘powerful connections’)
are those where the combination of two individual HRM activities has a more
positive eVect than the sum of each HRM activity’s individual eVects. An example
might be the combination of valid performance appraisals and a pay-for-perform-
ance system. Together these activities should have a much greater positive eVect
than using either activity alone. On the other hand,negative synergistic eVects
(‘deadly combinations’) refer to the situation where HRM activities actually work
against each other, undermining each other’s eVects. This could be the case, for
instance, if team-oriented work structures are combined with individual incen-
tives. Either of these activities alone may produce positive outcomes, but when
combined they could actually harm performance.
In any theoretical development focusing on either intra-HRM or inter-HRM
activity areaWt, it is essential that researchers develop speciWc hypotheses about the
nature of thatWt—something that has rarely been done in the SHRM literature. It is
not enough to simply say that a system of practices should have greater inXuence on
performance than the individual practices. Researchers must specify which practices
mustWt with each other and discuss the negative consequences, if any, of misWt. It is
unlikely that all HRM activities typically thought of as components of a ‘high-
performance work system’ have positive synergistic relationships with each other.
Some may have independent additive eVects, while others may have the positive
synergistic eVects so often discussed.
- 4 Levels of Analysis
The diVerent types of internalWt discussed above illustrate the complexities in
designing and measuring eVective HRM systems. Yet, they also highlight a related
394 sven kepes and john e. delery