SOUTHERN JOURNAL OF AGRICULTURAL ECONOMICS
JULY, 1974
SOME ISSUES CONCERNING SPECIFICATION AND INTERPRETATION
OF OUTDOOR RECREATION DEMAND MODELS *
Thomas A. Jennings and Kenneth C. Gibbs
Some currently popular procedures for analyzing
the demand for outdoor recreation makes use of
ancillary1 travel and on-site expenditures of
recreationists as proxy prices. It can yet regrettably
be asked whether the estimates produced by those
methods bear any resemblance to the
market-equivalent price-quantity relationships they
generally purport to quantify. To some unavoidable
extent this results from the necessary reliance upon
proxies, or surrogates, for both quantity and price
data. The ultimate value of proxy variables and of
estimated relationships between them lies in the
extent to which they resemble useful concepts. Past
research has been based largely on assumptions of the
resemblance.
A noteworthy weakness of existing lore on this
subject is the scarcity of accepted procedures for
specifying a recreation demand model and
interpreting (for purposes of practical application)
the estimates of such a model. The purpose of this
paper is to suggest some topics of needed research
and discussion toward founding consensus on certain
items of methodology which the writers deem worthy
of standardization. The suggestions pertain to three
issues: the choice of quantity proxies, the
approximation of price proxy variables, and time
constraints in recreation demand models. Also, a
suggested model is presented to help resolve some
apparent differences of opinion.
QUANTITY PROXIES
Choice of the recreation quantity unit is
necessarily a choice among proxies. A unit of
recreation is an intangible concept which can be
handled only in terms of some quantifiable
characteristics. Reflection inevitably reveals the
available choices of proxy to be debatably
representative of the outputs they purport to
quantify. Obviously, they represent nonhomogeneous
outputs. It is for reasons mainly to do with ease of
measurement, as compared to other tangible evidence
of recreation consumption, that the recreation
produce-unit has been defined as some amount of
time in which a visitor2 engages in some “typical” set
of activities at a given site.
Most outdoor recreation demand studies have
used either number of visits or length of stay as the
quantity variable. The most commonly employed
approach is that based on the original contribution of
Clawson [2]. Number of visits per population zone,
and more recently, as suggested by Brown and Nawas
[1], the number of visits per capita, represent the
dominant choice of quantity proxy among
economists using Clawson’s ideas. This choice
assumes variation in number of visits and none in the
length of stay per visit. The assumption has elements
of reality for certain unique recreational sites, where,
e.g., the visit is a once-in-a-lifetime or yearly affair.
Thomas A. Jennings is graduate research assistant in food and resource economics, and Kenneth C. Gibbs is assistant professor of
food and resource economics and of environmental engineering sciences at the University of Florida.
*Florida Agricultural Experiment Station Journal Series No. 5433 under State Project AS-Ol623.
ɪ “Ancillary” costs, for purposes of this paper (and based on methods under review here), refer to all costs that can be
associated with recreating on a given site. These consist of (1) travel costs, which are all costs incurred en route to a given site and
home again, and (2) daily on-site costs net both of user charges and normal “at-home” daily subsistence costs. Daily on-site costs
measure the value of a quantity of goods consumed on site regardless of where the goods were purchased. Day-use fees, campsite
fees, entry fees, and any other user charges would normally be considered as composing the supply price, or own-price, of
privately operated recreational facilities.
2The “visitor” in this quantum may refer to a single person, a family unit, or any other convenient decision-making
unit of humanity.
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