Section Fiveracy to conduct valid tests. Thus, it may be too much to expect
consistency across studies given the methodological challenges.
One of the paradoxes of research on the impact of human
resource practices is whether the adoption of such practices
produces superior performance or whether superior
performance and accompanying financial returns allow
companies to adopt better practices.^122 Unfortunately, much of
the research is cross-sectional and does not allow inferences of
causality. However, there have been a few recent studies that
employ longitudinal methodologies or at least lags between
adoptions of practices and outcome measures of firm
performance.^123 Lagged examinations of the performance
effects of human resource practices provide better evidence of
causality in that researchers can mark the implementation or
adoption of a practice at one point in time and then measure at
a later time whether the firm’s performance increased or
decreased. Nonetheless, such longitudinal studies still do not
allow researchers to rule out arguments of reverse causality.^124
Fortunately, there are a couple of reasons to question the
validity of the reverse causality argument. One is that there is
little motivation for high-performing firms to invest in these
human resource practices if they have reached such levels of
performance without the aid of such practices.^125 The second is
that some high-performance human resource practices have