How is single loss expectancy sle calculated

One year ago, the Mesusa Corporation conducted a threat evaluation and created a list of threats, the cost per incident and the projected frequency of occurrence. During the year, Mesusa decided to implement controls designed to reduce the cost per incidence and the number of threats. The spreadsheet, MesusaControls.xls, indicates thepre-control cost and frequency of occurrence, the cost of controls for each type of threat, and the post-control cost and frequency of occurrence. Calculate the AROs, theALEs and the CBA for this initiative, and return the completed spreadsheet. You can use the websites linked above to help you out. Please include your name on your spreadsheet before submission.

NOTE: The spreadsheet is provided below.

Submission Requirements

Format: Microsoft Excel
Font: Arial, 12-Point

Reference:

Instructor Notes
Students usually have trouble with calculating ALE, SLE, and ARO. You may want to take another look at this before you start your homework.

ALE is a common quantitative method for assessing risk.

The first step in calculating ALE is to calculate Single Loss Expectancy (SLE). --> SLE = asset value * exposure factor

ALE is then calculated by multiplying SLE by Annualized Rate of Occurrence (ARO). --> ALE = SLE * ARO

For example, to calculate the exposure factor, assume the asset value of a small office building and its contents is $2 million. Also assume that this building houses the call center for a business, and the complete loss of the center would take away about half of the capability of the company. Therefore, the exposure factor is 50 percent. The SLE is $2 million * 0.5 = $1 million

The ALE is then calculated simply by multiplying the SLE by the number of times the event is expected to occur in a year, which is called the annualized rate of occurrence (ARO): --> ALE = SLE * ARO

If the event is expected to occur once in 20 years, then the ARO is 1/20. Typically the ARO is defined by historical data, either from a company’s own experience or from industry surveys. Continuing our example, assume that a fire at this business’s location is expected to occur about once in 20 years. Given this information, the ALE is: $1 million * 1/20 = $50,000.