Can Technology Life-Cycles Be Indicated by Diversity in Patent Classifications? The crucial role of variety

TL;DR

This study investigates whether patent classification diversity can indicate technological life-cycles, revealing cyclical patterns driven by variety changes rather than technological disparity, and explores their relation to inventor activity.

Contribution

It demonstrates that patent classification diversity cycles are primarily due to changes in variety, not technological disparity, and links these cycles to inventor activity across different development phases.

Findings

Cyclical patterns in diversity are driven by variety fluctuations.

Technological disparity does not significantly influence these cycles.

Inventor activity correlates with diversity changes, especially in early development phases.

Abstract

In a previous study of patent classifications in nine material technologies for photovoltaic cells, Leydesdorff et al. (2015) reported cyclical patterns in the longitudinal development of Rao-Stirling diversity. We suggested that these cyclical patterns can be used to indicate technological life-cycles. Upon decomposition, however, the cycles are exclusively due to increases and decreases in the variety of the classifications, and not to disparity or technological distance, measured as (1 - cosine). A single frequency component can accordingly be shown in the periodogram. Furthermore, the cyclical patterns are associated with the numbers of inventors in the respective technologies. Sometimes increased variety leads to a boost in the number of inventors, but in early phases--when the technology is still under constructio--it can also be the other way round. Since the development of the cycles thus seems independent of technological distances among the patents, the visualization in terms of patent maps can be considered as addressing an analytically different set of research questions.