Commonly Used Formulas in Crime Statistics


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Important Data Facts

The table below lists which crimes are included in specific percent changes, crime rates, or clearances that are found in Florida's Uniform Crime Reports (UCR) or data sets. 
 
Crime (Total) Murder, Rape Aggravated Assault, Robbery, Burglary,
Larceny, and Motor Vehicle Theft
Violent Crime Murder, Rape, Aggravated Assault, and Robbery
Property Crime Burglary, Larceny, and Motor Vehicle Theft
Individual Crime Separate Individual Crime Types

Population data are from the Bureau of Economic and Business Research.

Percent Change

Percent change is used to demonstrate the difference between two values.  In UCR, it is typically used to show the change in the volume or rate of crime from one year to the next.  A positive percentage represents an increase in crime while a negative percentage describes a decrease in crime. 

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A word of caution:  In small counties with low numbers of crime, a small increase in crime can cause a large percent change.

A note about zero:  When the previous year's value is zero, a percent change is not calculated because division by zero is undefined.

Crime Rate

A crime rate is an indicator of reported crime standardized by population.  Florida's UCR Program uses the standard of 100,000.  The 2017 crime rate of 2,989.5 is properly interpreted as 2,989.5 total index crimes occured for every 100,000 people in Florida in 2017. 

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Clearance Rate

A clearance rate is the number of offenses cleared compared to the number of offenses reported in that same time period. 

Florida's UCR Program calculates clearance rate per 100 offenses.  The formula for this clearance rate is below. 
 

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Clearance Rate per 100 offenses may appear as "percent cleared" in documents published prior to 2017. 

Caution must be used in interpreting clearance rates.  Cases that are cleared in one year may have been reported offenses in a previous year.  Therefore, the number of offenses and the number of clearances are not a direct relationship of the outcome of cases that occured that year.  It is possible to have a clearance rate of greater than 100. 
 

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