The population-level view of interest group politics
Rather than attempting to draw conclusions about interest groups and lobbying by studying individual organizations, Gray and Lowery approached the subject from a higher perch, looking down on whole communities of groups in the fifty states. What, they asked, causes a state's population of groups to look the way it does, both in sheer numbers and in the variety of organizations representing people with varying political interests? Moreover, what effects do these population structures have on the advocacy strategies of the lobbyists these groups employ? Essentially Gray and Lowery pursue two goals. I will discuss the second later, but their first and arguably primary goal was to apply the theory of population ecology from biology to model the process by which interest group communities and sub-communities form, an effort culminating in their book The Population Ecology of Interest Representation (1996a). In their version of population ecology, itself derived from the theory's application in sociology (see Hannan and Freeman 1977, 1989), the likelihood that a new interest group forms is a function of the structure of the existing community of organized interests, and the resources supporting all of them, as much as it is the desires of some people to mobilize in defense of their political interests (Truman 1951), how attractive they find various material and purposive incentives (Clark and Wilson 1961; Olson 1965), and the charisma of group leaders (Salisbury 1969; Walker 1983).
Gray and Lowery's basic assumption is that existing group community structures feed back on future structures as the resources available to support those populations of interest groups shift and change over time. Thus the key variables of their Energy-Stability-Area (ESA) model derived from population ecology theory are the density of the current population, essentially the number of groups existing at any given time, and the resources available to support it. They define resources as the number of people seeking political representation through an interest group and the material resources available to fund the group. Group formation is also driven by the "energy" of the political system the group is embedded in, meaning the attention lawmakers are giving to issues perceived to be affecting potential group members' interests and the likelihood of a change in political party control. There are only so many people wanting to be represented by a particular group, so unless this number expands, which happens when their issues suddenly emerge on the government's agenda, few new groups are likely to form (Gray and Lowery 1996b).
One of Gray and Lowery's most interesting findings is that whether the group community remains in a stable equilibrium depends upon a state's economy. More people willing to spend money to join interest groups does not consistently lead to equivalent increases in the number of groups in a community. They instead find that, in the fifty states, the rate of increase in group numbers levels off at higher aggregate resource levels (measured as state GDP) (Gray and Lowery 2007). This is the density-dependence curve derived from ESA theory. The finding is interesting enough to warrant replication since their data is from 1997, which I do with 2011 data on state interest group populations from the Institute for Money in State Politics, and GDP and population data from the US Census Bureau. In Figure 5.1, I graph the number of groups in each state and state GDP, which reveals the same leveling-off pattern. Indeed, as Figure 5.2 shows, this leveling-off effect even emerges when just considering raw population data irrespective of their financial resources. Apparently group populations can only be so big. Numbers increase up to the state political system's "carrying capacity," at which point fewer newer organizations form and group deaths set in, causing the overall growth rate to level off.
Gray and Lowery went on to link their ESA model to other scholars' work by studying the structures of more narrowly construed sub-populations of groups, which, they argued, might be even more important to understanding interest group politics in each state than overall population size (Gray and Lowery 1993; Gray et al. 2005). Interest groups need dues-paying members to represent, but they cannot recruit just anybody. To mobilize and survive, each group or potential group markets itself only to a subpopulation of people with similar interests, what is sometimes called an interest-niche. The result, though, is several similar interest groups competing with each other to recruit members from the same limited pool of people with similar interests, though competition lessens when potential members are wealthy and can join several groups at once. This connects Gray and Lowery's ESA model to the work of William Browne (1990) and James Q. Wilson (1973) by refining and testing their arguments that a group thrives and survives by becoming the dominant, legitimate spokes organization for an interest.
Figure 5.1 Number of interest groups and state gross domestic product in 2011 Source: Institute for Money in State Politics and U.S. Census Bureau
Figure 5.2 Size of state populations and interest group communities in 2011 Source: Institute for Money in State Politics and U.S. Census Bureau
Interest-niches, however, are only one way to define a sub-population. We know that government officials can only focus on a few issues at a time (Kingdon 1984), so any burst of interest mobilization resulting from increased government attention to an issue, Gray and Lowery's energy term, will only affect those groups whose members are concerned with the issue. But the issue probably concerns people, and therefore groups, in several interest-niches. Transportation-oriented business associations and environmental groups, two distinctly different interest-niches, are both concerned with any proposed changes in the regulation of car and truck emissions. Greater government attention to an issue, and the policies addressing that issue, injects greater energy into all concerned interest-niches, causing greater mobilization and, consequently, the number of lobbyists lobbying those issues. Thus their work contributes to the study of issue-niches (or policy domains), sets of similar issues affecting multiple interest-niches, and links their work to research on cycles in issue attention (Baumgartner and Jones 1993), sub-governments (McConnell 1966; McCool 1990), and issue networks (Heclo 1978; Heinz et al. 1993).
After developing their ESA model over a period of years, Gray and Lowery started on a second goal: using it to study other questions in the field of interest group politics to see whether their population-level approach yielded new insights into how interest groups lobby. One extension was studying the effect of population-level variables on the strategies that individual group executives use to grow their organizations in resource-scarce environments (Gray and Lowery 1997). They find that leaders are less aggressive about redefining their organization's mission to ensure survival when they already dominate their interest- niche, having successfully recruited most of the potential members and pushed out competitor organizations, though they also sometimes shrink the size of their niche to achieve dominance. Another application is to study whether lobbyists join coalitions of groups or work alone in their pursuit of policy goals; the finding is that lobbyists tend to join when potential resources in their interest-niche are scarce (Gray and Lowery 1998).
