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Tree Ordinance Guidelines
Public polling
Uses:
Evaluating public attitudes and knowledge about trees and urban forest
management.
Materials needed:
Varies with the type of survey being conducted. See discussion below.
Notes:
The use of polling or surveying to assess public opinions, attitudes, beliefs,
and knowledge is well known to most people. On almost any day, the news media
report on the results of a poll or survey on some pressing topic. Polling can
be useful in assessing the knowledge and attitudes of the community with respect
to urban forestry issues. Properly designed polls can also be used to evaluate
whether an ordinance, educational program, or other management activity has brought
about changes in knowledge, attitudes, and practices in the community. Information
is normally gathered from the public either through interviews
or self-completed questionnaires.
Interviews
Compared with questionnaires, interviews generally have greater flexibility,
tend to elicit a higher response rate, and allow for more precise selection
of respondents. However, persons conducting interviews need to be carefully
trained to avoid introducing bias into the data.
Interviews may be conducted either in person or by telephone. Telephone
interviews are less expensive to conduct, allow for better sampling designs,
and can be used in conjunction with computers. Computer-assisted telephone
interviewing (CATI) systems are available and can increase the efficiency
of telephone interviews. A CATI system can be used to help the interviewer
adjust their questions based on information obtained during the interview,
and allows for the direct entry of data as the interview proceeds.
Self-completed questionnaires
Self-completed questionnaires have the advantage of being easier to administer
than interviews. Questionnaires are most commonly sent and returned by mail. Respondents
have more opportunity to think about questions or look up information for a self-completed
questionnaire than in an interview. While it is now possible to set up questionnaires
that would be accessed via the Internet, the sample responding to an Internet
survey may not be especially representative of the population as a whole or even
of the portion of the population that uses the Internet.
Typically, prior to the main survey mailing, ing, the questionnaire is pretested
on a small sample. Any problems that are identified in the construction
of the questionnaire can then be corrected.
Several techniques are commonly employed to boost the return rate for
mail surveys. These include the use of advance notification, attractive
first-class stamps rather than bulk postage, hand addressing, postage-paid
return envelopes, carefully-timed reminder postcards, and repeat mailings
of the questionnaire to nonrespondents. Token incentives included with
the survey are sometimes used to increase the return rate, but these will
also increase survey costs. Incentives may also introduce bias into the
returns if they tend to motivate some groups more than others.
Survey design considerations
Much of the difference in cost between the various methods is related to
the logistics of data collection, since design and analysis costs will
be similar. In-person interviews are generally the most costly and complex
surveys to conduct, due to the logistics of traveling door-to-door. The
cost of telephone surveys will vary with the length and complexity of the
survey and the sample size. Costs of the mail survey vary with the size
of the mailing and the number of follow-up mailings used.
Good survey design and sampling technique are critical to the success
of sample surveys conducted by any method. Care must also be taken in the
data collection and entry process, to avoid introducing errors. Finally,
even a well-conducted survey will not yield meaningful results if data
analysis and interpretation are flawed. Thus, while the concepts behind
public polling are reasonably straightforward, there is a fair amount of
art and science involved in conducting a useful study. Gross design and
execution errors can lead to meaningless or misleading results. More subtle
errors may not completely invalidate survey results, but can decrease the
reliability of the study.
If you are interested in conducting a public survey but lack the necessary
technical background or resources, there are various sources of assistance
available. Survey research units are associated with a number of state
college and university campuses. Some of these units,can contract with
cities or counties to design or conduct surveys. Others may provide information
or assist in studies on a cooperative basis. In addition, a number of private
firms specialize in conducting public surveys primarily for market research.
The scope of services provided and quality of work performed by these or
other consulting firms can vary widely, so careful shopping is advised.
Sampling considerations for public polling
For all but the very smallest municipalities, assessments of citizen attitudes
and knowledge will be based on polling a representative sample of the total
population. While most of the points noted under Sampling
from Populations apply, demographic factors also need to be considered to
avoid bias in the study design. For instance, Sommer
et al (1990) found that compared to younger citizens, older citizens were
more likely to have negative opinions about street trees in front of their homes.
It may be desirable to account for differences due to age, sex, sociological,
or other demographic factors in the survey. Such information may help local
governments decide whether education or other programs need to be targeted toward
certain segments of the population.
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Evaluation example: Homeowner attitudes toward trees
Sommer (1989) gives the following
example of how information from a mail survey can be used in urban forestry
management. European elms are a common street tree in the downtown area
of Sacramento, California. These large trees are attacked by elm leaf beetle
each summer, and the mess associated with these infestations had drawn numerous
complaints. In response, the city had initiated an elm replacement program.
This program provoked a public outcry, although not necessarily from neighborhoods
directly affected by elm replacement. The city conducted a mail survey of
householders in the downtown area and found that the majority of the property
owners liked their elm trees, and wanted them retained. This data was then
used to revise city policies regarding elms. |
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