I. INTRODUCTION  3

II. SECTORAL ANALYSIS  4

II.1 Sector-Level Productivity Growth  4

II.2 Shift-Share Decomposition  5

III. FIRM-LEVEL ANALYSIS  7

III.1 Frontier vs. Laggards: Definitions and Stylized Facts  7

III.2 The Decomposition of Frontier Productivity Growth  9

III.3 Diffusion and the Catch-Up from Laggards to Frontier Firms  11

IV. CONCLUSION  15

REFERENCES  16