- How is alcohol outlet density measured?
- How do you assess the relationship between alcohol outlet density and alcohol-related problems?
- How can Geographic Information System (GIS) mapping be used in understanding and reporting alcohol outlet density?
There are many methods for measuring outlet density. These methods vary greatly in complexity, resource requirements, and technical expertise needed. Each approach has advantages and disadvantages, which should be carefully considered before selecting a measurement strategy. It is also necessary to consider community characteristics and how the density measurement results will be used.
The general steps in measuring outlet density are:
- Obtaining data about licensed alcohol outlets
- Categorizing the alcohol outlets by type (e.g., on-premises or off-premises)
- Selecting the type(s) of alcohol outlet(s) that will be included in the measure
- Assigning geographic coordinates [latitude and longitude] to the alcohol outlets (note: this step is not necessary for all types of alcohol outlet density measures)
- Calculating alcohol outlet density using the selected approach
For additional information, please refer to the CDC Guide for Measuring Alcohol Outlet Density.
Depending on the intended use of the alcohol outlet density measurement, it may not be necessary to assess the relationship of outlet density to alcohol-related problems. Analysis of these relationships can be quite complex, and resource-intensive. However, these assessments may help policy makers determine what additional controls on alcohol outlet density may be needed to reduce the risk of alcohol-attributable harms in high-density areas.
As noted above, a variety of social, cultural, economic, and political factors contribute to the effect of alcohol outlet density in a community. It would therefore be beneficial to collect data on alcohol-related problems as well as community factors to determine whether there is a link between the problems and the specific alcohol outlet density landscape of a given community.
Alcohol-related problems can include alcohol-impaired driving and alcohol-related motor vehicle crashes as well as alcohol-related crime and violence, including sexual assaults, assaults, batteries, fights, intimate partner violence, and child maltreatment. To the extent possible, data regarding these problems should be geographically located so their link to alcohol outlet density can be assessed.11 Place-of-last-drink data, for example, can be collected by officers at driving under the influence (DUI) arrest sites or by DUI treatment programs as part of offenders’ intake interviews. Many place-of-last-drink surveys have found that up to one-half of those arrested for DUI offenses are coming from alcohol retail establishments prior to their arrest.39,40 Data generated from police calls for service, underage purchase compliance checks, and violations of Alcoholic Beverage Control laws (e.g., illegal sales to intoxicated persons) can be useful measures for identifying “hot spots” for crime and violence and determining whether there is a link between crime location and outlet density.
Epidemiologists in health departments can help community leaders determine the availability of data on these alcohol-related outcomes and identify ways to assess the potential link between alcohol outlet density and related problems.
CDC’s Guide for Measuring Alcohol Outlet Density provides more detailed information on how to assess alcohol outlet density in a community.
Although Geographic Information System (GIS) mapping tools are not essential for assessing the density of retail alcohol outlets, if such resources are available, GIS mapping can serve several roles in assessing alcohol outlet density. It can:
- Enable researchers to understand, manage, question, interpret, and visualize data in ways that can reveal relationships, patterns, and trends;
- Communicate the connections between community environments and public health problems; and
- Provide a strategy for determining the geographic coordinates of each alcohol outlet from a list of street addresses, computing numbers of alcohol outlets per given area, and calculating alcohol outlet density measures.11
An outlet density map can be augmented by creating overlays to illustrate particular features of the alcohol outlet density problem. For example, to identify patterns and relationships, researchers can overlay locations of police calls for service, incident reports for aggravated assaults, and alcohol outlet locations. Overlays can also identify the locations of sensitive land uses, such as schools, parks, and other youth-oriented environments. This can illustrate the proximity of particularly problematic alcohol outlet locations—outlets that may expose underage youth to alcohol and related marketing.
Caution should be exercised in interpreting outcome data, since mapping on its own does not provide a basis for asserting a causal link between crime, violence, and outlet density. Public health departments can assist by providing a trained epidemiologist to interpret the mapping data.
CDC’s Guide for Measuring Alcohol Outlet Density provides more detailed information about how to use GIS mapping to assess alcohol outlet density.