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Understanding Risky Facilities

Tool Guide No. 6 (2007)

by Ronald V. Clarke and John E. Eck

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In any large city just a handful of bars give the police far more trouble than all the rest put together. The same is true of many other types of establishments, such as schools, convenience stores, and parking lots. In each case, just a few produce far more crime, disorder, and calls for police assistance than the rest of the group combined. This phenomenon—called "risky facilities"—has important implications for many problem-oriented policing projects. In particular, it can help police focus their energies where they are needed most and can help in selecting appropriate preventive measures. This guide serves as an introduction to risky facilities and shows how the concept can aid problem-oriented policing efforts by providing answers to the following key questions.

  1. What are risky facilities?
  2. How widespread are risky facilities?
  3. How is the concept of risky facilities different from hot spots and repeat victimization?
  4. How can the concept of risky facilities assist problem-oriented policing projects?
  5. How can risk be measured?
  6. How is the concentration of risk among facilities calculated?
  7. Why do facilities vary in risk?
  8. How are risk factors identified for a particular group of facilities?
  9. How can risk be reduced?

What are Risky Facilities?

We open with a definition of facilities and provide some examples. We then discuss risky facilities and explain how this concept is related to other crime concentration theories.


Facilities are places with specific public or private functions, such as stores, bars, restaurants, mobile home parks, bus stops, apartment buildings, public swimming pools, ATM locations, libraries, hospitals, schools, parking lots, railway stations, marinas, and shopping malls.

Facilities vary greatly in the crimes they experience. Medical facilities, for example, are likely to have different types and levels of crime than do police booking facilities. In addition, there is likely to be a great variation within any broad category of facility. For example, although both are medical facilities, dental offices are likely to have different levels and types of crime than are emergency rooms. Because such distinctions are critical to the success of risky facility analyses, it is important to begin by carefully defining the type of facility that is to be examined; only then proceed to an examination of the type and frequency of crime that the particular type of facility experiences.

Risky Facilities

One important principle of crime prevention holds that crime is highly concentrated among particular people, places, and things; as this principle suggests, focusing resources on these concentrations is likely to yield the greatest preventive benefits. This principle has spawned a number of related concepts that are routinely used by police in problem-solving projects, including:

  • repeat offenders (individuals who commit a disproportionate amount of crime);
  • hot spots (areas and places where many crimes occur);
  • repeat addresses (locations with many crimes—a form of hotspot);
  • repeat victims (individuals who suffer a series of crimes in a short time span); and
  • hot products (items that are stolen more often than other products).

Risky facilities is another recently described theory of crime concentration that holds great promise for problem-oriented policing.1 The theory postulates that only a small proportion of any specific type of facility will account for the majority of crime and disorder problems experienced or produced by the group of facilities as a whole.

As a rule of thumb, about 20 percent of the total group will account for 80 percent of the problems. This is known as the 80/20 rule: in theory, 20 percent of any particular group of things is responsible for 80 percent of outcomes involving those things.2 The 80/20 rule is not peculiar to crime and disorder; rather, it is almost a universal law. For example, a small portion of the earth's surface holds the majority of life on the planet; a small proportion of earthquakes cause most earthquake damage; a small number of people hold most of the earth's wealth; a small proportion of police officers produce the most arrests; and so forth. In practice, of course, the proportion is seldom exactly 80/20; however, it is always true that some small percentage of a group produces a large percentage of any particular result involving that group. Later in the guide we will show you how to determine whether the 80/20 rule holds true for any particular group of facilities.

The 80/20 rule can be a useful initial assumption: when confronting a problem, start by assuming that most of the problem is created by a few individuals, places, or events. Although this first approximation is not always correct, it is probably correct more often than assuming that the problem is spread evenly across individuals, places, or events. Careful analysis can then test whether this starting assumption is correct.

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