the strength of dissimilarity favored the base state and vice versa. Since fewer states have NXW
lists with varying regulatory control, the emphasis in the above and the following sections is on
results from NXWS list.
Interest Groups’ Effects on Weed Regulation: Recall that the lobbying dissimilarity index
measures the political strength of an interest group, e.g., seed producer, relative to its counterpart
in the comparator state. For 1997, the effect of consumer lobbying in List 3 shows a pattern
similar to that observed for most agronomic and ecological indexes. That is, when the base
state’s consumer lobby is stronger than its counterpart in the comparator state, the two states
have lower regulatory overlap. Likewise, when the comparator state has a relatively stronger
consumer-lobby, the two states have larger regulatory differences. A similar effect is also
observed in the case of List 1. However, coefficients on consumer lobby index in other lists are
not significant with the exception of List 4, where a significant coefficient has the opposite sign
of that in List 3. For 2002, List 1 and 4 have the expected negative coefficient when
dissimilarity is biased towards the comparator state. Relating to equation (1), results from table 2
and 3 show a net negative effect of relative consumer lobby on regulatory congruence, which
implies that their eco-system preference gains dominate the market-consumption effect.
Dissimilarities in seed industry’s lobbying activities did not significantly affect noxious
weed regulations in 1997 (table 2). However, its lobbying effect becomes significant in List 2
and 4 for 2002 when the strength of the dissimilarity is biased toward the base state. That is, the
greater is the relative strength of the base state’s seed lobby, the larger the regulatory congruence
between the two states. Recall from equation (2) that seed producers benefit from price-
enhancement and agronomic-protection effects. However, we noted following equation (8) that
seed producers could perceive weed regulations as export barriers, in which case they likely
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