MEASURING SYSTEM USAGE - IMPLICATIONS FOR IS THEORY TESTING

There is widespread agreement among researchers that system usage, def ined as the utilization of information technology (IT) by individuals, groups, or organizations, is the primary variable through which IT af fects white collar performance. Despite the number of studies targeted at explaining system usage, there are crucial differences in the way the variable has been conceptualized and operationalized. This wide va riation of system usage measures hinders the efforts of MIS researcher s to compare findings across studies, thus impeding the accumulation o f knowledge and theory in this area. The purpose of this paper is to a ddress conceptual as well as methodological issues related to measurin g system usage. First, via LISREL measurement modeling techniques, we compare subjective and objective measures of system usage, namely, sel f-reported versus computer-recorded measures. Next, using a modified f orm of Davis' Technology Acceptance Model (TAM) as a nomological net, we test the nomological validity of these system usage constructs and measures. Results of the LISREL measurement and nomological net analys is suggest that system usage should be factored into self-reported sys tem usage and computer-recorded system usage. Contrary to expectations , these constructs do not appear to be strongly related to each other. Moreover, while self-reported measures of system usage are related to self-reported measures of TAM independent variables, objective, compu ter-recorded measures show distinctly weaker links. In the face of suc h counter-evidence, it is tempting to argue that research that has rel ied on subjective measures of system usage (for example, research conf irming TAM) may be artifactual. There are several alternative explanat ions, though, that maintain the integrity of TAM and studies that meas ure system usage subjectively. These alternative explanations suggest directions for further research as well as new approaches to measureme nt.