Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I even say who wrote them. If you have more recent summaries to add to this collection, send them my way I guess. Sorry for the ads; they cover the costs of keeping this online.
Walker. 1969. The diffusion of innovations among the American states. American Political Science Review 63:880-899.
States vary in how rapidly they tend to adopt new programs. This variation can be explained with the "tree" model. TREE MODEL: There are regional leaders of innovation who emulate and compete with one another (this is the center of the tree, the main few branches). The rest of the states are smaller branches, sorted out according to the regional pioneer from which they take their cues.
Innovation: When Walker speaks of innovation, he doesn't refer to anything more than adopting a new program. Even if a state adopts a new program begrudgingly and appropriates only $1000 to it, the state has adopted the new program. Furthermore, Walker refers only to programs adopted by state legislatures (not by bureaucrats).
The appendix lists 88 programs that were adopted by at least 20 state legislatures prior to 1965. For each program, Walker gives each state a percentile score (btw 0 and 1) based on the order in which it adopted the program (0 if first, 1 if last or still unadopted). He then averages each state's 88 program scores and subtracts the result from 1. Thus, the most innovative state (NY) scores 0.656; the least innovative state (MI) scores 0.298. PROBLEM: If the policies have an ideological tilt, then you would be giving a higher "innovativeness" score to more liberal states (which appears to be the case--see Table on pg 883). Many of the policies in the Appendix appear slanted toward urban and liberal innovativeness.
TWO COMPETING Xs FROM THE LIT:
Walker isn't so interested in determining which variable matters more as in his "tree" model. But still, both of these Xs seem to matter. X1 matters more.
THE TREE MODEL: PREMISES
Walker runs some factor analyses (of Y) and finds that the states really do sort out primarily by region (see Tables 5 and 6).
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