Preliminary Considerations
VISITATION DATA. A prerequisite to good spending estimates is good use information. A spending
study should therefore begin with a clear understanding of what use information is available and its accuracy. Since
total spending is usually estimated by multiplying the average spending per visitor times the number of visitors, one
cannot estimate a change in total spending without first estimating the number of visitors affected by a given action.
It is important that the units for which use is available are compatible with the unit of analysis for which spending is
estimated in order to properly multiply the two figures. One often must include a few key questions in addition to
the spending questions to convert between the units for use and spending. Party size and length of stay information
are the most common variables for converting spending data to a per person, per party, per trip, or per night basis.
Other survey variables can sometimes be useful in correcting for biases in the use data, e.g., when visitation data are
not adjusted for multiple entries to a park, commercial traffic, or other problems. In estimating impacts of park
visitor spending on a region around the park, length of stay in the region is more critical than length of stay in the
park. If thought out in advance, these variables can be estimated as part of the spending survey.