ASU Density Mapping Grid Mapp

1- Density mapping, grid mapping and graduated symbol mapping are three methods of mapping, used by analysts to, visually, depict crime in a, given, area.

Density Mapping: Is used when analysts identify problem areas and use a graduated color map to represent the exact locations and concentrations of crime within the problem area.

Graduated Symbol Mapping: Is used when an analyst has identified a problem area and uses graduating sized symbols to represent the concentration of crime in a location. Often, different sized dots will represent the crime location and concentration, with smaller dots representing less concentration and larger dots representing larger concentrations.

Grid Mapping: Is used when analysts identify a problem area and use a standard sized grid to overlay onto a map. Often used in conjunction with graduated color shading to represent location and concentration of crimes.

According to Santos, density mapping, unlike grid mapping and graduated symbol mapping, does not limit the user to a specific, pre-determined, geographical area. Instead, density mapping follows the flow of hot spots in the area and uses geographic features known to local law enforcement and other users (Santos, 2017)

Grid maps rely on dot points set on an overlay gid on a map of a given area. Graduated symbol maps use dots like a grid map, but the dots vary in size to represent concentrations of crime. Density mapping uses graduated colors to represent concentrations of crime, but unlike grid maps and graduated symbol maps, density maps do not identify the location of any specific incident. Graduate Symbol maps appear to be a blending of both grid maps and density maps.


Santos, R. B. (2017). Crime Analysis and Crime Mapping (4thth ed.). Tall Oaks, CA: Sage. Retrieved from:

2- The 80/20 principle or the Pareto principle was first discovered by Vilfredo Federico Damaso Pareto because he first understood that 20% of his peapod produced 80% of his peas. He then applied this same logic in Italy towards realizing 20% of people owned 80% of the land. The 80/20 principle is the imbalance of input and output. In crime analysis the 80/20 principle basically is used to state for every 80% of consequences in a situation, comes from 20% of a cause. According to Bowers (2014), Results suggest that internal theft problems precede external ones and that the physical concentration of chronically risky facilities is a particularly strong predictor of external theft problems. An example that helped me understand these logic more was when I applied it to the way crime happens. For example; 20% of criminals commit 80% of crimes.

Using 80/20 to explain identifying problem location for a crime analyst is important because they are able to understand where most of the crimes happen as well as where most victims and offenders are living in the areas. According to Santos (2016, p. 410), Crime analysts use the 80/20 principle to identify problem locations where the problem has concentrated in order to guide police in prioritizing where their responses should be implemented. By law enforcement having a guide towards the problem areas, it can help with implementing programs that can reduce the crime within these hot spot areas. According to Weisburd et al. (2017), wider application of hot spots policing can have significant impacts on overall levels of crime in urban areas.


Bowers, K. (2014). Risky Facilities: Crime Radiators or Crime Absorbers? A Comparison of Internal and External Levels of Theft. Journal of Quantitative Criminology, 30, 389-414. doi:

Santos, R. B. (2016). Crime Analysis With Crime Mapping (4th ed.). Los Angeles, CA: SAGE Publications, Inc. Retrieved from…

Weisburd, D., Braga, A. A., Groff, E. R., & Wooditch, A. (2017). Can Hot Spots Policing Reduce Crime In Urban Areas? An Agent- Based Stimulation. Criminology, 55(1), 56-89. doi:

3- According to The Arizona State University Center for Problem Oriented Policing, the 80/20 rule is a principle that suggests, a large percentage of outcomes is generated by a small percentage of input (Arizona State University Center for Problem Oriented Policing, 2020). According to Santos, the 80/20 rule suggests that by identifying a small proportion of areas, victims or offenders where a large proportion of crime occurs police can better use their resources to maximize their effectiveness against crime (Santos, 2017, pgs. 82-83).

Both definitions are confusing and unclear, at least to me. The best way I could explain the 80/20 rule is, 80% of crime occurs in 20% of the jurisdictional area. This ratio is not set in stone, in fact according to Santos, it’s rarely ever actually 80/20 (Santos, 2017, pg. 83). I think the principle is sound though. If, as analysts, we can identify a small area of the town or city, that accounts for a large portion of crime, we can apply the 80/20 rule. By applying the 80/20 rule we can attempt to assign agency resources, to best address the largest percentage of crime.

The 80/20 principle reminds me of another ratio principle. The 90/10 rule. That’s to say, 90% of crime is committed by 10% of the population. I think both principles are correct, and I have seen them at work on patrol. In my jurisdiction there are two areas of the city that generate a large majority of the crime we deal with. These two areas account for a large majority of our attention and time and generate a large majority of our arrests. The crime in these two areas, seem to be committed by a handful of the same people, repeatedly. What some might call, “frequent flyers”. These two areas of my jurisdiction account for 80% of the crime in our city, but the area, itself, only accounts for 20% of the city. The 10% of offenders we deal with, in these two areas, account for about 90% of the crime, also.


Learn if the 80-20 rule applies. (2020). In Arizona State University Center of Problem Oriented

Policing. Retrieved from,80%20percent%20of%20the%20outcomes.&text=Calculate%20the%20percentages%20of%20the,%2C

Santos, R. B. (2017). Crime Analysis and Crime Mapping (4thth ed., pp. 82-83). Tall Oaks, CA: Sage. Retrieved from

Please respond to these student discussion boards, each response should 150+ words followed by its own references. APA style and schoraly jornals for sources are required

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