The industrial age was bound to end when the microprocessor was invented. Even though the classical economic theory applies for today as well as for the 1960s, the last thirty years were symptomatic by the change of the fundamental characteristics of the economy and information technology plays a key role in this process. The aim of this thesis was to describe the principles and micro- and macroeconomic phenomena present in the New Economy of today, the challenges that the companies face in this environment and, finally, to conduct a cross-industry analysis on the impact of IT on company's performance, namely value-added. The empirical results did not show any clear patterns among the industries and therefore no significant relationship between the share of information technology assets of total assets and company's value-added could be proven. One of the reasons for that could be the technical issues regarding the statistical measurement of IT which also remains the biggest challenge for the researchers in this field.

Today, with various technology and business standards, organizations face rapid changes in both internal and external environments. To be able to rapidly respond to such changing environments, integration of software systems has entered among the top priorities of many organizations. However, despite extended use of software integration, methods for estimating the business value of implementing such integration are still missing. Besides presenting a conceptual model to define the benefits of systems integration and related causal relationships, this study proposes a method for measuring such benefits in monetary terms. In particular, we  demonstrate how a mathematical programming technique called Data Envelopment Analysis (DEA) can be used to evaluate the business value of software integration. Our method is illustrated using data from 12 organizations. The results indicate significant productivity gains by integrating software systems, which represent the value of software integration in organizations.