WS - E - Conducting Community Surveys

If the subgroup of interest is a very small proportion of the overall population, then tripling or quadrupling the sample size may be in order. In these situations, simple random sampling is prohibitively expensive since you need more and more interviews & and a more efficient method of probability sampling should be used. Professional assistance should be sought under these conditions. If the victimization experience you seek to examine is more common than the previous example, you may call fewer people. For example, if the victimization experience is estimated at 15%, looking at Table 1, you will see that you only need to call 200 persons to find 30 persons with that type of experience. How representative is the sample? As telephone numbers are randomly generated for the survey, no advance information is available about the population. While the generation of random numbers (RDD) will provide a defensible sampling strategy, the randomness alone will be insufficient to insure that the final sample is actually representative of the jurisdiction's population. Nonrepresentativeness may occur either in the original sampling frame if, for example, low-income persons or minorities are less likely to have phones, or in the non-responses or refusals if victimized persons or some other group are less likely to participate in the survey. The resulting level of error in the survey estimates will depend on how many persons are missed and how different they are from those that you are able to interview. Missing a large portion of a distinctive subgroup in the population can greatly reduce the usefulness of the survey data. For most police agencies, some demographic characteristics of citizens are of critical importance in collecting information. The exposure of citizens to police and their opinions of police, as well as victimization experience, vary based on demographic and neighborhood characteristics. Thus information about these characteristics must be collected during any survey and must be monitored as the survey is being conducted to make sure that enough respondents with those characteristics are being surveyed. For most police agencies, these relevant characteristics may include gender, age, race, and income level. Additional variables may be critical in a particular jurisdiction. Once the survey is administered and demographic characteristics of the respondents are developed, these findings can be compared with census data for your jurisdiction to ensure that respondents are representative. For groups which may be underrepresented in the final sample, the responses may be weighted to increase their relative proportion for the entire sample. Conducting Community Surveys 15