In determining risk, one can use the equation:

risk = [vulnerability x probability of occurrence x cost (or magnitude)] / mitigation or preparedness

Vulnerability is determining the threats and what could cause a hazard within a system.  The weak points within the system must be determined to understand where there exists a possibility of occurrence.  The probability of occurrence depends on how likely hazardous situation is to occur.  If a situation were to occur, there will be a cost, whether it be money, lives, safety, or the inability to re-inhabit land.  Risk can be lessened if there is a level of preparedness.  If the masses are prepared for tragic events to occur, they will have less of an impact, leaving less damage.

The risk of improperly calibrated AED machines can be calculated using this same equation.  An Automated External Defibrillator (AED) is battery-operated and depends on a computer analysing information sent to it from electrodes.  If the computer is improperly calibrated, this could cause a major problem in attempting to returning the individual's heart back to a normal rhythm.  This leaves the computer/electrode system to be a point of vulnerability.  Since AEDs are not needed very often, the probability using one is very low, but to then have the machine fail as well decreases even further the chance of failure.  The cost of a non working machine is the death of the individual.  Preparedness for this failure can include training in methods of resuscitation so as to not rely on the AED should it fail.

The masses may not anticipate a failure of a medical device, they take for granted that they will work.  Media portrays some systems or structures as safe, while others are shown as dangerous, and therefor the public has negative connotations of them.