at specific points in time. In previous research studies on park use, the most convenient approach was to count park users up to three or four times per day at threehour intervals for a minimum of four days, including at least two weekdays and one weekend day. The aggregated results could provide a relatively accurate assessment of park use over a one-week period. However, the limitation of these closely spaced observations is that the findings may not generalize to different seasons when the parks may be used (or unused due to inclement weather) or when the attraction of the park might vary based on seasonal sports activities. Although jurisdictions may have hundreds of parks, it isn’t necessary to collect data on each park to understand how the parks are being used. A park system may be interested in tracking how its facilities are used. It may want to get a lot of detail about a specific park or about specific areas within one or more parks. Typically, a sampling strategy consists of randomly selecting a small percentage of the parks. A random selection should help ensure that the sample is representative and the findings may be applicable to all parks in the system, even those that were not specifically studied.
City Parks Alliance
Data collection training for the National Study of Neighborhood Parks.
parks) is different from the sampled population (staffed parks), and the sample would not be representative for the target population. In practice, a perfect match between the sampled and target population is usually very difficult. However,
evaluators should make the best efforts to align these two populations. Second, whenever possible, we should always use a probability sample instead of a convenience sample. With a probability sample, everyone in the population has
Sampling Theory and Representativeness of Distant Observations Conceptually, a sample is representative if it can be used to accurately estimate the characteristics of the target population, which is the actual interest for measurement. Among the many technical issues in sampling theory, there are three critical issues in achieving representativeness. First, the sampled population, from which the sample is drawn, should match with the target population as best as it can. For example, suppose that we are interested in studying all parks and facilities managed by the park department. Because of logistical constraints, we may decide to sample only the parks with onsite staff. Then, the target population (all
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