Based on that data, we summarized whether the states in the area were above or below the national average of membership levels. All five states are well below the national average in membership in environmental groups. The other four weigh in at less than half of their expected membership. This low level might be considered when making environmental policy in Arkansas. On average, membership is about half of the expected membership, for all environmental groups.
Many people join multiple environmental groups.
We count their dues for as many groups as they join, since their revealed preference is higher than people who join only one group. Hence we do not consider multiple membership to be a problem with our estimation technique. Once again, this omission makes any error on the side of keeping our estimate low. All other major population centers within the area are counted. This potentially underestimates our intrinsic value significantly, since rural non-members have a value that is not reflected proportional to their urban counterparts.