Equation for calculating a rate

The most commonly used rates are per 1000 population or per 1000 households values. Rates are often standardised into a per annum value. The equation for calculating a rate of this type can be written as,

((12/A) * B) * 1000/C

where,

A – is the number of months that your crime or disorder count covers

B – is the number of crimes/disorder events within your geographic area (e.g. enumeration district or ward)

C – is the value of your denominator within your geographic area (e.g. the total population, or residential household count in your enumeration district or ward).

The value ‘12’ in the equation represents the number of months in one year (i.e. used for standardising the rate to a per annum value). The ‘1000’ value is used to calculate a ‘per 1000’ rate.

Click here for an example which shows how domestic burglaries were calculated in an enumeration district over an eight month period.