Understanding Basic Crime Analysis Statistics
Statistical measures are can be used in a variety of ways in crime analysis. Each statistical measure is employed at a specific time to study particular trends in data. Most statistical measures lose meaning when the data in question is non-numeric or quantitative (Analysts, Massachusetts Association of Crime, 2008).
The crime rate expresses crime as a proportion of the population in the area under study. The index crime rate computed from the UCR statistics is likely to be lower than that computed using Reported Crimes. this is because the UCR statistics usually exclude other kinds of crimes whereas the Reported Crime includes them. The proportion of the population selected for computing crime rates should be realistic. Using a large proportion when the area under study is small could give the illusion that the crime rate is very low. Sometimes it may be necessary to use different proportions to compare two areas realistically.
The types of crime understudy should also be considered. It is not prudent to mix murder and petty theft statistics. One area might have high petty theft and very low murder rates. However, when the crime rate is computed, an analyst might be tempted to conclude that the area has a very high crime rate. It would be a misrepresentation. The police could end up giving too much attention to an area that does not need it and neglect the area that requires attention (Analysts, Massachusetts Association of Crime, 2008).
The range refers to the difference between the peak and least variable in data. It is a general measure that gives an analyst a rough idea of what to expect. It cannot be used in computing other statistical measures. However, the range should not be disregarded as it can aid in identifying errors in data.
Analysts should be familiar with measures of central tendency as they are useful in many ways. The mode indicates the variable that has been repeated most in a distribution. Supposing the data under study was the number of crimes in various sections of a city. The mode would indicate in which area most crimes occur, thus enabling the department to assign enough officers (Dr. Bobba, 2008).
The mean is the mathematical average of the terms in the distribution. In cases of normal distributions, the mean can be used as a representative of the entire set of data. Alternatively, the median may be used where the data is skewed. Standard deviation is a statistical measure used alongside the mean. It shows how far from the mean the variables are dispersed. When presented with a set of statistics, an analyst can employ all these measures and come up with meaningful conclusions (Dr. Bobba, 2008).
Tactical Analysis
Police reports are the major source of information for tactical analysis. The data in the reports often contain unexplained gaps and an analyst has to employ critical thinking to fill these gaps. Critical thinking involves problem solving and judgment. Police reports provide information about a crime that has occurred. Employing logical thinking could help the analyst to draw meaningful conclusions. Logical thinking involves drawing reasonable conclusions based on what one knows.
Statistical analysis is supported by police reports. The reports contain the time the crime was committed. It could be very useful in temporal analysis. An analyst can be able to construct a schedule for the offender using the clues from the police report. After establishing the frequency of the crime, the analyst can predict when next the criminal will strike. This prediction depends on the frequency of the crime. The distribution could be random, clustered, or uniform. Random and clustered distributions are more difficult to predict than uniform distributions (International Association of Crime Analysts, 2009).
Police reports may also contain a record of events that occur alongside the crime. It could call for correlation analysis to find out whether this is a coincidence or a causal relationship. Correlation analysis employs statistics to determine whether there is a relationship between the occurrences of two separate events. The analyst should be aware of misleading correlation analysis. If the analysis shows a strong correlation, the analyst should question whether the relationship is causal and logical.
The tactical analysis aims at generating a forecast of crime in the short run, such that police can be able to stop the criminal before they strike. It can be done using various statistical measures. Linear timing forecasts and cyclical timing forecasts can be employed to predict when the crime might happen next.
Interpolation can aid in the construction of a suspect’s schedule of activities. Since police reports may not contain all the information about a suspect’s activities, employing statistical methods may help the analyst to complete the puzzle. The analyst must not be prejudiced in drawing his conclusions. Teams should avoid groupthink because they will end up missing important points. The usefulness of police reports in tactical analysis cannot be overstated. They are the basis of this type of crime analysis (International Association of Crime Analysts, 2009).
References
Analysts, Massachussets Association of Crime. (2008). Introduction to Crime Analysis. Web.
Dr Bobba, R. (2008). Crime Analysis With Crime Mapping. Chicago: Sage Publications.
International Association of Crime Analysts. (2009). Work Samples. Web.