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Operations research, or
operational research (OR) in British usage, is a discipline that deals with the application of
advanced analytical methods to help
make better decisions. Further, the term operational analysis is used in the British (and some British Commonwealth) military as an
intrinsic part of capability development, management and assurance. In particular, operational analysis forms part of the Combined Operational Effectiveness and Investment Appraisals, which support British defense capability acquisition decision-making.
It is often considered to be a sub-field of
applied mathematics.The terms
management science and
decision science are sometimes used as synonyms.
Employing techniques from other mathematical sciences, such as
mathematical modeling,
statistical analysis, and
mathematical optimization, operations research arrives at optimal or
near-optimal solutions to complex decision-making problems. Because of its emphasis on human-technology interaction and because of its focus on practical applications, operations research has overlap with other disciplines, notably
industrial engineering and
operations management, and draws on
psychology and
organization science. Operations research is often concerned with determining the extreme values of some real-world objective: the
maximum (of profit, performance, or yield) or minimum (of loss, risk, or cost). Originating in military efforts before World War II, its techniques have grown to concern problems in a variety of industries.
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Beginning in the 20th century, study of inventory management could be considered the origin of modern operations research with
economic order quantity developed by
Ford W. Harris in 1913. Operational research may have originated in the efforts of military planners during World War I (convoy theory and
Lanchester's laws).
Percy Bridgman brought operational research to bear on problems in physics in the 1920s and would later attempt to extend these to the social sciences.
Modern operational research originated at the
Bawdsey Research Station in the UK in
1937 and was the result of an initiative of the station's superintendent,
A. P. Rowe. Rowe conceived the idea as a means to analyse and improve the working of the
UK's early warning radar system, Chain Home (CH). Initially, he analysed the operating of the radar equipment and its communication networks, expanding later to include the operating personnel's behaviour. This revealed unappreciated limitations of the CH network and allowed remedial action to be taken.
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In the World War II era, operational research was defined as "a scientific method of providing executive departments with a quantitative basis for decisions regarding the operations under their control". Other names for it included operational analysis (UK Ministry of Defence from 1962) and quantitative management.
During the Second World War close to 1,000 men and women in Britain were engaged in operational research. About 200 operational research scientists worked for the
British Army.
Patrick Blackett worked for several different organizations during the war. Early in the war while working for the
Royal Aircraft Establishment (RAE) he set up a team known as the "Circus" which helped to reduce the number of
anti-aircraft artillery rounds needed to shoot down an enemy aircraft from an average of over 20,000 at the start of the
Battle of Britain to 4,000 in 1941.
In 1941, Blackett moved from the RAE to the Navy, after first working with
RAF Coastal Command, in 1941 and then early in 1942 to the
Admiralty.
Blackett's team at
Coastal Command's Operational Research Section (CC-ORS) included two future
Nobel prize winners and many other people who went on to be pre-eminent in their fields. They undertook a number of crucial analyses that aided the war effort. Britain introduced the
convoy system to reduce shipping losses, but while the principle of using warships to accompany merchant ships was generally accepted, it was unclear whether it was better for convoys to be small or large. Convoys travel at the speed of the slowest member, so small convoys can travel faster. It was also argued that small convoys would be harder for German
U-boats to detect. On the other hand, large convoys could deploy more warships against an attacker. Blackett's staff showed that the losses suffered by convoys depended largely on the number of escort vessels present, rather than the size of the convoy. Their conclusion was that a few large convoys are more defensible than many small ones.
While performing an analysis of the methods used by
RAF Coastal Command to hunt and destroy submarines, one of the analysts asked what colour the aircraft were. As most of them were from Bomber Command they were painted black for night-time operations. At the suggestion of CC-ORS a test was run to see if that was the best colour to camouflage the aircraft for daytime operations in the grey North Atlantic skies. Tests showed that
aircraft painted white were on average not spotted until they were 20% closer than those painted black. This change indicated that
30% more submarines would be attacked and sunk for the same number of sightings. As a result of these findings Coastal Command changed their aircraft to using white undersurfaces.
Other work by the CC-ORS indicated that on average if the trigger depth of aerial-delivered
depth charges (DCs) were changed from 100 feet to
25 feet, the kill ratios would go up. The reason was that if a U-boat saw an aircraft only shortly before it arrived over the target then at 100 feet the charges would do no damage (because the U-boat wouldn't have had time to descend as far as 100 feet), and if it saw the aircraft a long way from the target it had time to alter course under water so the chances of it being within the 20-foot kill zone of the charges was small. It was
more efficient to attack those submarines close to the surface when the targets' locations were better known than to attempt their destruction at greater depths when their positions could only be guessed. Before the change of settings from 100 feet to 25 feet,
1% of submerged U-boats were sunk and
14% damaged. After the change,
7% were sunk and 11% damaged. (If submarines were
caught on the surface, even if attacked shortly after submerging, the numbers rose to
11% sunk and 15% damaged). Blackett observed "there can be few cases where such a great operational gain had been obtained by such a small and simple change of tactics".
Bomber Command's Operational Research Section (BC-ORS), analyzed a report of a survey carried out by
RAF Bomber Command. For the survey, Bomber Command inspected all bombers returning from bombing raids over Germany over a particular period. All damage inflicted by German
air defences was noted and the recommendation was given that armour be added in the most heavily damaged areas. This recommendation was not adopted because the fact that the aircraft returned with these areas damaged indicated these areas were not vital, and adding armour to non-vital areas where damage is acceptable negatively affects aircraft performance. Their suggestion to remove some of the crew so that an aircraft loss would result in fewer personnel losses, was also rejected by RAF command. Blackett's team made the logical recommendation that the armour be placed in the areas which were completely untouched by damage in the bombers which returned. They reasoned that the survey was biased, since it only included aircraft that returned to Britain. The untouched areas of returning aircraft were probably vital areas, which, if hit, would result in the loss of the aircraft. This story has been disputed, with a similar damage assessment study completed in the US by the Statistical Research Group at Columbia University and was the result of work done by
Abraham Wald.
When Germany organized its air defences into the
Kammhuber Line, it was realized by the British that if the RAF bombers were to fly in a
bomber stream they could
overwhelm the night fighters who flew in individual cells directed to their targets by ground controllers. It was then a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimize RAF losses.
The
"exchange rate" ratio of output to input was a characteristic feature of operational research. By comparing the number of flying hours put in by Allied aircraft to the number of U-boat sightings in a given area, it was possible to redistribute aircraft to more productive patrol areas. Comparison of exchange rates established "effectiveness ratios" useful in planning. The
ratio of 60 mines laid per ship sunk was common to several campaigns: German mines in British ports, British mines on German routes, and United States mines in Japanese routes.
Operational research doubled the on-target bomb rate of
B-29s bombing Japan from the
Marianas Islands by
increasing the training ratio from 4 to 10 percent of flying hours; revealed that
wolf-packs of three United States submarines were the most effective number to enable all members of the pack to engage targets discovered on their individual patrol stations; revealed that
glossy enamel paint was more effective camouflage for
night fighters than traditional dull camouflage paint finish, and the
smooth paint finish increased airspeed by reducing skin friction.
On land, the operational research sections of the Army Operational Research Group (AORG) of the
Ministry of Supply (MoS) were landed in
Normandy in 1944, and they followed British forces in the advance across Europe. They analyzed, among other topics, the effectiveness of artillery, aerial bombing and anti-tank shooting.
Scientists in the United Kingdom including
Patrick Blackett (later Lord Blackett OM PRS),
Cecil Gordon,
Solly Zuckerman, (later Baron Zuckerman OM, KCB, FRS),
C. H. Waddington,
Owen Wansbrough-Jones,
Frank Yates,
Jacob Bronowski and
Freeman Dyson, and in the United States with
George Dantzig looked for ways to make better decisions in such areas as
logistics and training schedules.
