In the knowledge-based economy, the accumulation of technological knowledge is undoubtedly the core competency to reinforce the competitiveness of individual firms and to raise the innovation capability of social and economic systems. Thus far, however, only single or fragmentary indicators, such as R&D expenditure, R&D stock, the number of researchers and the number of R&D employees have been adopted to measure the amount of technological knowledge. In this research, we suggest an approach for aggregating and structuring respective indicators. Applying correlation and factor analysis, we examine the relationship among nine conventional proxy measures for technological knowledge and present a new approach for gauging an aggregated measure.