Policy Innovation Adoption Across the Diffusion Life Course

Abstract

This study develops and tests a theory of the diffusion life course using a dataset of 566 policies adopted between 1960 and 2016. Previous small‐N studies found differences between leaders and laggards, but broader innovation theory points to five stages of adoption: innovation, early adoption, early majority, late majority, and laggard. This study demonstrates that predictors of policy adoption change throughout the diffusion life course. Neighbor adoptions matter early in the life course but are supplanted by the consistent effect of ideological learning across all stages. The results confirm that less professionalized states tend to adopt later. Finally, state wealth and population size are increasingly important as policies spread. These results have implications for our understanding of when and why states adopt policy innovations. They also illustrate the substantial opportunity for political science and public policy researchers to draw from broader theories.

Anti-poverty policy and health: Attributes and diffusion of state earned income tax credits across U.S. states from 1980 to 2020

“…As noted, the overall diffusion pattern of this public policy roughly approximates the conventional S-curve of cumulative adoptions over time-a few innovator states slowly start the process, followed by a period of more rapid spread, ending with a gradually slowing spread to the remaining laggard states. Given that a number of states have enacted EITC laws in the past few years (Table 1), combined with the fact that 40% of states do not yet have a state-level EITC, suggests that we likely have not yet reached the top of the S-curve-that is, a complete leveling off of the adoption rate [49,50].…”

“…A broader question that arises whenever observing the spread of a particular state policy is: What drives the adoption of this distinct policy in a given state at a given time, and what drives the pattern of diffusion to other states? Understanding the complex mix of causal factors affecting state-level policy adoption across time is of theoretical and practical importanceand is an important focus of current and future research in political science [50]. There is a wide range of conceptually distinct plausible drivers of policy adoption [50].…”

“…Understanding the complex mix of causal factors affecting state-level policy adoption across time is of theoretical and practical importanceand is an important focus of current and future research in political science [50]. There is a wide range of conceptually distinct plausible drivers of policy adoption [50]. In broad categories these drivers include, at a minimum, geospatial effects, role of multiple dimensions of political and social ideologies, effects of coercion and incentives (from higher level federal government, as one key example), and resource availability and distribution [50].…”

“…There is a wide range of conceptually distinct plausible drivers of policy adoption [50]. In broad categories these drivers include, at a minimum, geospatial effects, role of multiple dimensions of political and social ideologies, effects of coercion and incentives (from higher level federal government, as one key example), and resource availability and distribution [50]. Moreover, recent research suggests drivers of policy adoption likely vary in their relevance across the adoption curve (i.e., across time within each adoption curve) [50].…”

“…In broad categories these drivers include, at a minimum, geospatial effects, role of multiple dimensions of political and social ideologies, effects of coercion and incentives (from higher level federal government, as one key example), and resource availability and distribution [50]. Moreover, recent research suggests drivers of policy adoption likely vary in their relevance across the adoption curve (i.e., across time within each adoption curve) [50]. There remains considerable poorly understood heterogeneity in policy adoption speed, and continuing research on causes of adoption patterns, both for EITC and more generally for all state-level policies, is warranted.…”