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(c) Alan Sheehan B.E. 2006
SARCalc 3 is a MS Excel workbook for Land Search Control by managing search probabilities. By sound application of probability theory, difficult search management decisions can be made, justified and documented.
It is recommended SARCalc be saved as an Excel Template prior to use.
This ensures that the original file is not inadvertently modified, or overwritten and lost during use. It also simplifies the creation of new SARCalc files for each search.
To create a new SARCalc Workbook, open MS Excel, File, New... and select SARCalc3 from your list of templates.
Before doing anything else, save the new SARCalc Workbook with a unique filename. For example, you could save the file as SARyymmddn, where yy = last 2 digits of the year, mm = the month, dd = the day of the month and n = the sequential number of the workbook created for that day. It is very unlikely that you would need to create more than one SARCalc workbook on the one day for the one search, so you may choose a simpler file naming convention. The file naming convention you use is entirely up to you.
Start with the Overview page first.
In cell B2 enter a self evident name for the search. This can be changed later if desired.
In cell B3 enter the date. Remember (ctrl)(;) will automatically insert the current system date.
In cell E3 enter the date on which search planning started. For the initial workbook, this is likely to be the same as for cell B3, but for subsequent workbooks it will be different.
When the initial search area is known and divided into appropriate search sectors, enter the search sector names in the range B6..B65. It is recommended that search sectors be designed to be of a size that can be searched by a search team in 2 to 4 hours. Larger search sectors slow down the cycle of feedback from searchers to SARCalc making the search too slow to respond to clues and find the subject quickly.
Notes relevant to the search sectors can b entered into the range G5..G65 at any time.
The Initial POAs are calculated from the four Initial POAs pages (I POA 1 to I POA 4). If this is the second or later workbooks for the search, the final POAs from the previous workbook can be copied and pasted, or linked into the range C5..C65 over the formulae. More on that later.
The Current POA and Cumulative POD data is calculated automatically from the search data. The System Message column displays automated messages based on the search data, such as when to expand the search area and when a sector is effectively searched.
Four Initial POA pages are provided (I POA 1 to I POA 4). Each search planner should use a separate Initial POA page. The workbook combines the results of all used pages into the consensus Initial POAs in the Overview page. It is recommended that between 2 and 4 planners be used to estimate the Initial POAs to avoid tunnel vision and give reasonable weight to all possible scenarios.
Each Initial POA page is set up for scenario analysis with up to 10 scenarios. Notice the search Sector names appear automatically in the range B9..B69 from the overview page.
Enter the date in cell B3.
Enter the search planner's name in cell B4.
Enter the time in Cell E3, and the organisation the planner belongs to in cell E4.
Enter a brief description of each scenario in the range C6..L6, and the corresponding weighting for each scenario in the range C7..L7 below it. The weighting is an estimate of how likely the planner feels that scenario is to happen.
For each scenario, the planner now assesses how likely it is that the subject will be in each sector if that scenario has occurred.
Should the planner only want to do a basic "gut feel" estimate of POAs without a full scenario analysis, simply enter the estimates POAS in the range C9..C69, but make sure a number between 1 and 9 inclusive is entered into cell C7.
The results of the four Initial POA pages are combined using the Mattson Method to give the Initial POAs in the Overview Page.
Operational Search Data is entered on one page per Operational Period. Ten Operational Period Pages are provided in each workbook (OP1 to OP10). Ideally the operational period should be between 2 and 4 hours duration. Each search sector should be searchable within the operational period (though SARCalc does handle late data OK, incomplete data at the time of tasking for the next operational period could result in inappropriate use of resources).
The Date, Time Start and Time End relate to the operational period. The Planner's name is entered in cell B4 and their organisation in D4.
The resources column (C9..C68)is used to track the resources assigned to each search sector for the operational period.
The Initial POAs (D8..D68) are the POAs at the start of the Operational Period. For the first Operational Period they are taken from the Overview Page. For each subsequent Operational Period they equal the final POAs of the previous Operational Period. This column is not protected (notice it is white, not light blue) to allow the cells in this range to be edited to accommodate expansion of the search area or splitting of sectors.
The Estimated Probability of Detection (POD) (E9..E68) is where the Expected POD of the resource is entered as they are tasked in order to calculate the Probability of Success (POS) (F9..F69). This obviously occurs as resources are tasked at the start of the operational period. Note that when searching for missing persons, a relatively low POD is desirable to increase the rate of search area coverage in order to find the subject alive. Typically a POD of around 30% is ideal however realistically this can vary from 10% to 50%. For forensic searches, thoroughness usually more desirable so that evidence is not destroyed in subsequent passes, so PODs of 90% on the first operational period are the desired target.
At the completion of the operational period the search resources are debriefed, and the Retrospective POD is entered in the range G9..G68 and any clues are processed.
When the Retrospective POD is updated, the Cumulative POD (column H) is also calculated. Cumulative POD indicates how well the sector has been searched taking into account the cumulative effects of all the resources utilised in all previous operational periods.
The following figure shows the Clues section of the Operational Period page (columns L..V).
When a clue is found, enter a description or clue identifier in the range M6..V6. Each column ideally represents 1 clue, so up to 10 clues per operational period are easily accommodated.
The first decision to make about a clue, is how authentic it is - in other words - how sure you are that it actually belongs to the search subject. A clue that definitely belongs to the search subject is authentic, and one that does not belong to the search subject is not authentic. A scale is provided to estimate the authenticity of the clue. Clue authenticity represents one facet of the importance of the clue. The estimate of clue authenticity is entered into the range M7..V7.
The next series of decisions to make about each clue is to interpret what the clue means about the location of the subject within each search sector. This is done by entering a score in rows 8 to 68.
When the clues have been fully entered and assessed, the clue factors for each sector are calculated in column I. This in turn updates the Interim POA* in column J. Once the Interim POA* are normalised they become the Final POA for the Operational Period (column K).
The Final POAs from one operational period become the Initial POAs for the next. The only deviation from this is if they need to be changed in order to add new search sectors or to split existing sectors. For this reason the Initial POAs column is not protected.
When it is necessary to expand the search area, decide the most likely parts of the ROW to make into new sectors. Remember to size the sectors appropriately so that resources can effectively search the sector within the time available in the operational period. Once the new sectors have been decided, enter the sector names/descriptions on the Overview page.
Return to the Operational Period page where the sectors are being introduced and enter the estimated Initial POAs for the sectors. Remember, that the total of the Initial POA's for the new sectors must be subtracted from the Initial POA for the ROW. Negative or zero POAs are not valid. The sum of the Initial POAs after splitting the sector must still add up to 100%.
Occasionally the need may arise to split an existing sector. This should not be a common occurrence, and is usually due to a lack of foresight or poor decision making when assigning the sector boundaries.
Once the new sectors have been decided, add their names/descriptions to the bottom of the sector list on the Overview page.
Return to the Operational Period page where the new sectors will come into effect, and decide what proportions to divide the Initial POA for the original sector into for each new sector. Assign the new Initial POAs to the new sectors, and make the Initial POA for the original sector equal zero. Ignore the original sector from here on. The sum of the Initial POAs after splitting the sector must still add up to 100%.
When the search goes beyond 10 operational periods, it will be necessary to start a new workbook.
In Excel, select File, New... and select a new SARCalc3 workbook from the available templates.
On the Overview page, enter the Search Name and Date. Copy the Date "Planning Started" from the original workbook. Replace the formulae in the Initial POAs range (C5..C65) with the values of the Final POAs from page OP10 of the previous workbook. This can be done by either copying and pasting the data, or by linking the data.
Ignore the Initial POA estimation pages (I POA 1 to I POA 4).
SARCalc3 includes a Clue Log page to document clues. This page is not linked into the calculations performed by SARCalc. It's use is therefore optional.
Each clue occupies a single row in the clue log. The fields should be self evident.
SARCalc3 also includes a Running Sheet page. This page is not linked into the calculations performed by SARCalc. It's use is therefore optional.
The running sheet allows an operator to utilise the date and time stamp functions in MS Excel to accurately record times of actions and communications. The From and To fields relate to the sender and receiver of communications. The Message field is for recording details of the message or action.
It is not likely that an effective log can be kept with this running sheet while running SARCalc3 for search control. If it is to be used, it is recommended that a separate operator use the running sheet on a separate PC (and workbook). On completion of the search the Running Sheet can be copy-and-pasted into the official search workbook.
Cumulative POD: Cumulative Probability. A measure of the thoroughness of the search through a sector taking into account all the resources in all the previous operational periods. A sector is not considered "searched" until the Cumulative POD exceeds 90%.
Estimated POD: The Probability of Detection that a sector will/should be searched at. This is important information to tell the team leader how thoroughly versus how quickly to search the sector/area.
Normalisation: The process of scaling estimated probabilities (e.g. Interim POA*) so that the sum of all probabilities equals 100%.
POA: Probability of Area. The probability that the search subject is in the given search sector or area.
POD: Probability of Detection. The probability that the search resource will find the subject if the subject is in the area or sector.
POS: Probability of Success. This is an estimate of the probability that the search subject will be found during the current operational period. POS = POA*Estimated POD.
Retrospective POD: An estimate made by the Resource Team Leader as to how thoroughly the sector/area was searched. Typically assessed by asking the question "If the subject was in your area, what were your chances of finding the subject?"
ROW: Rest of the World. This is everywhere outside the search area.