Discussion Paper Series 2024-E-17

Innovation Choice, Product Life Cycles, and Optimal Trend Inflation

Hiroshi Inokuma, Mitsuru Katagiri, Nao Sudo

This study revisits the old and ongoing challenge of identifying the optimal trend inflation rate, using a novel model that incorporates a firm's innovation choices, product life cycles, and the interplay of the two factors. We construct an endogenous growth model with sticky prices, where firms have two options: to be an innovator or to be a follower. An innovator causes creative destruction, forcing all the incumbents to exit, and becomes a monopolist in its sector. A follower enters an existing sector by offering a product that is slightly different from the incumbent's products, inducing a product life cycle within the sector. Trend inflation impacts the firm's decision regarding which of the two options to choose by changing expected markups and profits. We show that the optimal trend inflation rate could exceed zero as it mitigates potential innovator losses upon the entry of followers, which in turn depresses the incentives for firms to be followers, promoting creative destruction and faster economic growth.

Keywords: Sticky prices; Optimal inflation; Product life cycle; Innovation; Productivity growth; Markups


Views expressed in the paper are those of the authors and do not necessarily reflect those of the Bank of Japan or Institute for Monetary and Economic Studies.

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