Perform Risk / Analysis
In conducting the risk assessment of the property exposure, metrics are used. These metrics are a scoreboard. This allows the security professional to make the best possible risk-based solutions by quantitatively exposing areas of vulnerability.
The goal for deference is to convince potential criminals that a successful crime is unlikely due to a strong defense. The first line of security for buildings, offices and other physical spaces successfully use environmental design to deter threats. Anything that increases the likelihood that criminal actions will be observed and reported to police or security personnel is a deterrent.
Courtesy / Protection / Safety
Effective deterrents place psychological and / or physical barriers in the perpetrators path and imply there will be no opportunity to successfully commit their crime.
In spite of your best efforts, some criminals may not be put off by security measures. In these instances, your next line of defense is to delay completion of the crime. The longer it takes the perpetrator to complete the crime the greater is the probability they will be observed and apprehended.