Improved Operational Testing and Evaluation and Methods of Combining Test Information for the Stryker Family of Vehicles and Related Army Systems Phase II Report (2004) / Chapter Skim
Currently Skimming:
Phase I Report: Operational Test Design and Evaluation of the Interim Armored Vehicle
Phase I Report: Operational Test Design and Evaluation of the Interim Armored Vehicle
Pages 103-212
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 103... ...
Phase I Report Operational Test Design and Evaluation of the Interim Armored Vehicle
|
From page 105... ...
, the Panel on Operational Test Design and Evaluation of the Interim Armored Vehicle considers the Stryker IOT an excellent opportunity to examine how the defense community might effectively use test resources and analyze test data. The panel's judgments are based on information gathered during a series of open forums and meetings involving ATEC personnel and experts in the test and evaluation of systems.
|
From page 106... ...
OVERALL TEST PLANNING Two specific purposes of the IOT are to determine whether the IBCT/ Stryker performs more effectively than the baseline force, and whether the Stryker family of vehicles meets its capability and performance requirements. Our primary recommendation is to supplement these purposes: when evaluating a large, complex, and critical weapon system such as the Stryker, operational tests should be designed, carried out, and evaluated with a view toward improving the capabilities and performance of the system.
|
From page 107... ...
In particular, as pointed out in the panel's letter report (Appendix A) , the current test design calls for the IBCT/Stryker trials to be run at a different time from the baseline trials.
|
From page 108... ...
In support of such an approach, we present a number of specific technical suggestions for test design, including making use of test design in learning and confirming stages as well as small-scale pilot tests. Staged testing, presented as an alternative to the current design, would be particularly useful in coming to grips with the difficult problem of understanding the contribution of situation awareness to system performance.
|
From page 109... ...
Thus, the Department of Defense in general and ATEC in particular should give a high priority to developing a contractual relationship with leading practitioners in the fields of reliability estimation, experimental design, and data analysis to help them with future IOTs. In summary, the panel has a substantial concern about confounding in the current test design for the IBCT/Stryker IOT that needs to be addressed.
|
From page 110... ...
separating the operational test into at least two stages, learning and confirmatory. · ATEC shoulcl consider applying to future operational testing in general a two-phase test design that involves, first, learning phase studies that examine the test object under different conclitions, thereby helping testers design further tests to elucidate areas of greatest uncertainty and importance, ancl, seconcl, a phase involving confirmatory tests to address hypotheses concerning performance vis-a-vis a baseline system or in comparison with requirements.
|
From page 111... ...
· When specific performance or capability problems come up in the early part of operational testing, small-scale pilot tests, focused on the analysis of these problems, should be seriously considered. For example, ATEC should consider test conditions that involve using Stryker with situation awareness degraded or turned off to determine the value that it provides in .
|
From page 112... ...
System maturation should be expedited through previous testing that incorporates various aspects of operational realism in addition to the usual developmental testing. · Because it is not yet clear that the test design and the subsequent test analysis have been linked, ATEC should prepare a straw man test evaluation report in advance of test design, as recommended in the panel's October 2002 letter to ATEC (see Appendix A)
|
From page 113... ...
is whether the various missions, types of terrain, and intensity of conflict are the correct choices for operational testing to support the decision on whether to pass Stryker to full-rate production. One can imagine other missions, types of terrain, intensities, and other factors that are not varied in the current test design that might have an impact on the performance of Stryker, the baseline system, or both.
|
From page 115... ...
It focuses on two aspects of the test design and evaluation: (1) the measures of performance and effectiveness used to compare the force equipped with the Stryker with a baseline force and (2)
|
From page 116... ...
. The mobility of the IBCT is to be provided by the Stryker vehicle (until recently referred to as the interim armored vehicle)
|
From page 117... ...
The Army notes that the Stryker-GFE system must provide a particular capability, termed situation awareness, to offset the above-mentioned platr 1torm llmltatlons:
|
From page 118... ...
The mounted systems equipped with Force XXI Battle Command, Brigade and Below (FBCB2) and other enhancements provide the IBCT a larger internetted web of situational awareness extending throughout the IBCT area of operations.
|
From page 119... ...
Key performance requirements, defined in more detail in the ORD, are that the Stryker vehicles must: · maximize commonality of components and subcomponents across few . configurations; · possess an "internetted interoperable capability" that enables it to host and integrate existing and planned Army command, control, communications, computers, intelligence, surveillance, and reconnaissance (C4ISR)
|
From page 120... ...
Although we have major concerns about the appropriateness of using the LIB as an alternative comparison force, because our primary responsibility is to address broader statistical and test design issues, we have taken this choice of baseline to be a firm constraint. PANEL CHARGE The Stryker will soon be entering an 1 8-month period of operational test and evaluation to determine whether it is effective and suitable to enter
|
From page 121... ...
Committee on National Statistics convene a panel of experts to examine its plans for the operational test design and subsequent test and evaluation for the IBCT/Stryker. This resulted in the formation of the Panel on Operational Test Design and Evaluation of the Interim Armored Vehicle.
|
From page 122... ...
We also reviewed in detail all key government documents pertaining to the operational testing of the IBCT/Stryker, including: the Operational Requirements Document, · the System Evaluation Plan, · the Test and Evaluation Master Plan, · the Organizational and Operational Description, · the Failure Definition and Scoring Document, · the Mission Needs Statement, · the Operational Mode Summary and Mission Profile, and sample Operational Orders applicable to operational tests. With the cooperation of the management and staff of ATEC, the panel conducted two forums and two subgroup meetings at which ATEC staff presented, in response to panel queries: descriptions of measures of effectiveness, suitability, and survivability under consideration for the initial operational test; details of the proposed experimental design; planned use of modeling and simulation; and planned methods of analysis of data that will result from the testing.
|
From page 123... ...
Box 1-1 presents a number of terms used in operational testing. After additional forums and deliberations, the panel intends to prepare a second report that addresses the applicability of combining information from other sources with that from the IBCT/Stryker initial operational test.
|
From page 125... ...
The third issue is whether the current operational test design can provide adequate information on how to tactically employ the IBCT/Stryker system. For example, how should the greater situational awareness be taken advantage of, and how should the greater situational awareness be balanced against greater vulnerability for various types of environments and against various threats?
|
From page 126... ...
Even if the statistical issues addressed in this report were to be mitigated, we cannot determine whether the resulting operational test design would be fully informative as to whether Stryker should be promoted to full-rate production.
|
From page 127... ...
A key element in this series of tests is the operational testing, commencing with the initial operational test (IOT)
|
From page 128... ...
2. The incorporation of developmental test data, manufacturer test data, and historical data in the evaluation.
|
From page 129... ...
When ATEC is assigned the responsibility for performing test and evaluation for a given system, several documents are developed: · the test and evaluation master plan, · the test design plan, · the detailed test plan, · the system evaluation plan, and · the failure definition and scoring criteria. Testers perform a developmental test on the early production items in order to verify that the specifications have been met or exceeded (e.g., a confirmation, by noncontractor personnel, of the product verification test results on delivered systems)
|
From page 130... ...
This extrapolation can involve the expected outcomes at different locations, with different force sizes, or with a full brigade being present, for example. C7 ' 1 1 TEST PROCESS Scripting In the test design documents, each activity is scripted, or planned in advance.
|
From page 131... ...
The role of the contractor in logistics support is always a key issue: contractors often maintain systems during introduction to a force, ancl both the level of "raining of Army maintenance personnel ancl the extent of contractor involvement in maintenance can affect force ancl system performance during operational testing. The contractor will not be present cluring actual combat, so it could be arguccl that the contractor should not be permitted in the areas reserved for the JOT.
|
From page 132... ...
Its. One salient example ofthe effects of resource constraints on the Stryker IOT is the limited number of options available to test the situation awareness features of the Stryker's C4ISR (command, control, communications, computers, intelligence, surveillance, and reconnaissance)
|
From page 133... ...
for each test is also controlled for and is essentially a replication, since both the IBCT and the baseline force will execute the same scenarios. The panel has commented in our October 2002 letter report (Appendix A)
|
From page 134... ...
134 o ._ Cal o ._ ._ Cal o ._ .° .° o .~ _ ~ _ o %~= s.' to ~- ~ 1 .
|
From page 135... ...
; that term will be used here. The IBCT/Stryker initial operational test (JOT)
|
From page 136... ...
Thus, performance could include, for example, the Stryker vehicle's survivability, reliability, and lethality; the IBCT's C4ISR (command, control communications, computers, intelligence, surveillance, and reconnaissance) ; and situation awareness, among other things.
|
From page 137... ...
Although numerical values of mission-level MOEs provide quantitative information about the degree of mission success, the analysis of operational test results should also be a diagnostic process, involving the use of various MOEs, MOPs, and other information to determine why certain mission results occurred. Using only summary MOE values as a rationale for decision recommendations (e.g., select A over B because MOEA = 3.2 > MOEB = 2.9)
|
From page 138... ...
may also be applied across these mission types, although objective casualty-related MOEs are especially useful for evaluating SSC engagements, in which both the IBCT and the OPFOR casualties are indicators of mission success. Casualty-related measures are less commonly applied to SOSE missions, in which enemy losses may have little to do with mission success.
|
From page 139... ...
However, to do so, care must be taken to ensure that the SME ratings have the usual properties of subjective data used in other scientific studies, that is, that they can be calibrated, are repeatable, and have been validated. One good way to support the use of SME ratings in an IOT is to present a careful analysis of SME training data, with particular attention paid to demonstrating small inter-SME variance.
|
From page 140... ...
Casualty-Related Measures In this section we discuss some of the casualty-related MOEs for evaluating IBCT mission success, appropriate for both combat and SOSE missions, but particularly appropriate for SS C-like engagements in which both sides can inflict significant casualties on each other. Specifically, we discuss the motivation and utility of three casualty ratio MOEs presented by ATEC in its operational test plan.
|
From page 141... ...
It is relatively straightforward to convert a system loss to personnel casualties by knowing the kind of system and type of system kill. Loss Exchange Ration A measure of force imbalance, the loss exchange ratio (LER)
|
From page 142... ...
Force Exchange Ratios The LER indicates the degree of mission success in tactical-level engagements and allows an examination of the impact of different weapon systems, weapon mixes, tactics, etc. At this level, each alternative in a study traditionally has the same initial U.S.
|
From page 143... ...
This suggests considering a measure that "normalizes" casualties with respect to initial force size, which gives rise to the force exchange ratio (FER)
|
From page 144... ...
~ . Initial force ratios.
|
From page 145... ...
4. The RLR motivates commandeers "to seek an optimum tradLe-o~ IDetween friendly survivors and enemy casualties." This does not appear germane to selecting an MOE that is intended to measure the degree of mission success in the IBCT JOT.
|
From page 146... ...
These casualties occur when rounds fired at the enemy go astray (for a variety of possible reasons, including erroneous intelligence information, false detections, target location errors, aiming errors, weapons malfunction, etch. Accordingly, we recommend that ATEC report, as one MOE, the number of such casualties for IBCT/Stryker and the baseline force and also compute a fratricide frequency (FF)
|
From page 147... ...
This statement points directly to the factors that have been used in the current test design: terrain (rural and urban) , OPFOR intensity (low, medium, high)
|
From page 148... ...
The reasons for performance differences can be divided into two categories: Stryker capabilities and test factors. Stryker capabilities include situation awareness (which contributes to survival by avoidance)
|
From page 149... ...
Two other categories of measures that could be more useful in assessing performance differences attributable to situation awareness, responsiveness, and maneuverability are scenario-specific and system degradation measures.
|
From page 150... ...
provided by ABCS to commander and staffs? MOE 4-2-4 How well did the ABCS allow the commander and staff to gain and maintain situation awareness/understanding?
|
From page 151... ...
These kinds of measures readily allow for direct comparison to the baseline, and definitions can be written so that they are measurable. System Degradation Measures: Situation Awareness as an Experimental Factor The other type of measure that would be useful in attributing differences to a specific capability results from degrading this capability in a controlled manner.
|
From page 152... ...
· IBCT systems should be able to rapidly "hand off" targets to enhance unit kill rates at all ranges. · Using combinations of the above situation awareness advantages, IBCT units should be capable of changing traditional attacker-defender battle dynamics favoring the defender at long ranges and the attacker at shorter ranges.
|
From page 153... ...
It is not sufficient to rely on test conditions (e.g., the unreliability of the hardware itself) to provide opportunities to observe missions without situation awareness.
|
From page 154... ...
Reliability Criterion 1-3 states: "The Stryker family of interim armored vehicles (excluding GFE components and systems) will have a reliability of 1,000 mean miles between critical failures (i.e., system aborts)
|
From page 155... ...
; · infant mortality, durability/wearout, and random failures (types and consequences of these three types of failure modes) ; · durability accelerated testing and add-on armor; and · random failures, GFE integration, and scoring criteria.
|
From page 156... ...
Although the different Stryker vehicle variants will probably have different failure modes, there is a reasonable possibility that information across these modes can be combined when assessing the reliability of the family of vehicles. In the current TEMP, failure modes from developmental test (DT)
|
From page 157... ...
Infant Mortality Operational tests, to some extent, serve the purpose of helping to uncover and identify unknown system design flaws and manufacturing problems and defects. Such "infant mortality" problems are normally corrected by making design or manufacturing changes or through the use of sufficient burn-in so that the discovered infant mortality failure modes will no longer be present in the mature system.
|
From page 158... ...
Some wearout failure modes (not necessarily weight-related) may show up during the JOT, but they are likely to be underrepresented compared with steady-state operation of the Stryker fleet, because the vehicles used in the IOT will be relatively new.
|
From page 159... ...
The reliability of the GFE integration is of special concern. The blending of GFE with the new physical platform may introduce new failure modes at the interface, or it may introduce new failure modes for the GFE itself due to the rougher handling and environment.
|
From page 160... ...
2. Although ratio MOE values may be useful in assessing degrees of mission success, both the numerator and the denominator should be reported.
|
From page 161... ...
14. Situation awareness shoulcl be introduced as an explicit test cone ition.
|
From page 162... ...
20. Accelerated testing of specific system components prior to operational testing should be considered in future contracts to enable testing in shorter and more realistic time frames.
|
From page 163... ...
Since the operational test design for the IBCT/ Stryker is now relatively fixed, the discussion is intended to demonstrate to ATEC the advantages of various alternative approaches to operational test design that could be adopted in the future, and therefore the need to reconsider these constraints. This is followed by a brief description of the current design of the IBCT/Stryker initial operational test (IOT)
|
From page 164... ...
IMPROVED OPERATIONAL TESTING AND EVALUATION (LIB) from modeling or simulation, developmental testing, or the performance of similar systems is used to impact the allocation of test samples in the test design.
|
From page 165... ...
Multiple Objectives of Operational Testing and Operational Test Design: Moving Beyond Statistical Significance as a Goal Operational test designs need to satisfy a number of objectives. Major defense systems are enormously complicated, with performances that can change in important ways as a result of changes in many factors of interest.
|
From page 166... ...
The hope is that the other measures of interest will be related in some fashion to the primary measure, and therefore the test design to evaluate the primary measure will be reasonably effective in evaluating most of the remaining measures of interest. (If there are two measures of greatest interest, a design can be found that strikes a balance between the performance for the two measures.)
|
From page 167... ...
, we discuss here modifications to the sample size, test design, and test factor levels. Sample Size Given that operational tests have multiple goals (i.e., learning and confirming for multiple measures of interest)
|
From page 168... ...
Therefore, the issue of providing specific averages in the evaluation needs to be separated from allocation of test samples to scenarios. As indicated above, test designs go hand-in-hand with test goals.
|
From page 169... ...
While this may be less clear for the specific scenarios under which IBCT/Stryker is being tested, allocating 42 scenarios to the baseline system may be inefficient compared with the allocation of greater test samples to IBCT/Stryker scenarios. Testing with Factors at High Stress Levels A general rule of thumb in test design is that testing at extremes is often more informative than testing at intermediate levels, because information from the extremes can often be used to estimate what would have happened at intermediate levels.
|
From page 170... ...
Alternatives to One Large Operational Test In the National Research Council's 1998 report Statistics, Testing, and Defense Acquisition, two possibilities were suggested as alternatives to large operational tests: operational testing carried out in stages and small-scale pilot tests. In this section, we discuss how these ideas might be implemented by ATEC.
|
From page 171... ...
When specific performance or capability questions come up in the early part of operational testing, small-scale pilot tests, focused on the analysis of these questions, should be seriously considered. For example, the value of situation awareness is not directly addressed by the current operational test for IBCT/Stryker (unless the six additional missions identified in the test plan are used for this purpose)
|
From page 172... ...
The primary disadvantage of the current design is that there is a very strong chance that observed differences will be confounded by important sources of uncontrolled variation. The panel discussed one potential source of confounding in its October 2002 letter report (see Appendix A)
|
From page 173... ...
In addition, ATEC designed the operational test for IBCT/Stryker to support comparisons relative to attrition at the company level. ATEC provided analyses to justify the assertion that the current test design has sufficient power to support some of these comparisons.
|
From page 174... ...
Then ATEC modeled SME ratings scores for both IBCT/Stryker and the baseline using linear functions of the controlled variables from the test design. These linear functions were chosen to produce SME scores in the range between 1 and 8.
|
From page 175... ...
ATEC's analysis argues that since 0.75 is larger than 0.40, the operational test will have sufficient statistical power to find a difference of 0.75 in SME ratings. The same argument was used to show that interaction effects that are estimated using test sample sizes of 18 or 12 would also have sufficient statistical power, but interaction effects that were estimated using test sample sizes of 6 or 4 would not have sufficient statistical power to identify SME ratings differences of 0.75.
|
From page 176... ...
As a result, these statistical power calculations are unlikely to be reliable. Furthermore, not only are casualties not independent, but even if they were, they should not be rolled up across mission types.
|
From page 177... ...
2. ATEC should consider applying to future operational testing in general a two-phase test design that involves, first, learning phase studies that examine the test object under different conditions, thereby helping testers design further tests to elucidate areas of greatest uncertainty and importance, and, second, a phase involving confirmatory tests to address hypotheses concerning performance vis-a-vis a baseline system or in comparison with requirements.
|
From page 178... ...
3. When specific performance or capability problems come up in the early part of operational testing, small-scale pilot tests, focused on the analysis of these problems, shoulcl be seriously consiclerecl.
|
From page 179... ...
one simulated battalion commander supported by three simulated companies.
|
From page 180... ...
Why does the Strykerequipped force outperform the baseline force? It is important to avoid "rolling up" the many measures into a small number of summary measures 180
|
From page 181... ...
. Another dichotomy that is relevant when analyzing data is that between the use of formal statistical methods (like significance tests)
|
From page 182... ...
. In either case, statistical significance tests or confidence intervals are often used to determine if the observed improvement provided by the new system is too large to have occurred by chance.
|
From page 183... ...
If we think of the analysis as comprising a confirmatory and exploratory phase, then it should be possible to restrict significance testing to a small number of outcomes in the confirmatory phase. The exploratory phase can focus on investigating the scenarios for which improvement seems greatest using confidence intervals and graphical techniques.
|
From page 184... ...
. Such graphs can identify sets of outcome measures that show the same pattern of responses to the factors, and so can help confirm either that these measures are all correlated with mission success as expected, or may identify new combinations of measures worthy of consideration.
|
From page 185... ...
provide an excellent discussion of statistical methods for reliability. A key aspect of complex systems like Stryker that impacts reliability, availability, and maintainability data analysis is the large number of failure modes that affect reliability and availability (discussed also in Chapter 31.
|
From page 186... ...
The discussion of general principles in the preceding section comments on the importance of defining the appropriate unit for data analysis. The ATEC-designed evaluation consists basically of 36 missions for the Strykerequipped force and 36 missions for the baseline force (and the 6 additional missions in the ATEC design reserved for special studies)
|
From page 187... ...
The intended ATEC analysis focuses on the difference between IBCT/ Stryker force outcomes and baseline force outcomes for the 36 missions.
|
From page 188... ...
Additional parameters measure the degree to which IBCT/Stryker improvement varies by mission type, mission intensity, location, company, etc. These additional parameters can be tested for significance or, as suggested above, estimates for the various factor effects can be reported along with estimates of their precision to aid in the judgment of practically significant results.
|
From page 189... ...
Statistical significance tests are useful in the confirmatory analysis comparing the Strykerequipped and baseline forces. In general, however, the issues raised by the 1998 NRC panel suggest that more use should be made of estimates and
|
From page 190... ...
This highlights the need for improved data collection regarding vehicle usage. In particular, data should be maintained for each vehicle over that vehicle's entire life, including training, testing, and ultimately field use; data should also be gathered separately for different failure modes.
|
From page 191... ...
From a practical point of view, it is clear that several of the ideas put forward in NRC 1998 for improvement of the measures and test design cannot be implemented in the IBCT/Stryker IOT due to various constraints, especially time limitations. However, by viewing the Styker test as an opportunity to gain additional insights into how to do good operational test design and evaluation, our panel hopes to further sharpen and disseminate the ideas contained in NRC 1998.
|
From page 192... ...
exhibited under these conditions. For this reason, Conclusion 2.3 of NRC 1998 states: "operational testing is essential for defense .
|
From page 193... ...
Moreover, designs used in operational testing are not usually constructed to inform the actual decisions that operational test is intended to support. For example, if a new system is supposed to outperform a baseline in specific types of environments, the test should provide sufficient test sample in those environments to determine whether the advantages have been realized, if necessary at the methods.
|
From page 194... ...
This maturation should be expedited through previous testing that incorporates various aspects of operational realism in addition to the usual developmental testing. The role, then, for operational testing would be to confirm the results from this earlier testing and to learn more
|
From page 195... ...
and (6) use of small-scale screening or guiding tests for collecting information on test planning." Also, as mentioned in Chapter 4, it is not yet clear that the test design and the subsequent test analysis have been linked.
|
From page 196... ...
For example, if IBCT/Stryker is intended primarily as an urban system, more replications should be allocated to urban environments than to rural ones. We understand ATEC's view that its operational test designs must allocate, to the extent possible, replications to environments in accordance with the allocation of expected field use, as presented in the OMS/
|
From page 197... ...
1051: The Department of Defense and the military services should give increased attention to their reliability, availability, and maintainability data collection and analysis procedures because deficiencies continue to be responsible for many of the current field problems and concerns about military readiness. While criticizing developmental and operational test design as being too focused on evaluation of system effectiveness at the expense of evaluation of system suitability, this recommendation is not meant to suggest that operational tests should be strongly geared toward estimation of system suitability, since these large-scale exercises cannot be expected to run long enough to estimate fatigue life, etc.
|
From page 198... ...
Making use of the information on situation awareness collected during training exercises and in contractor and developmental testing in the operational test design would have helped in the more comprehensive assessment of the performance of IBCT/Stryker. For example, allocating test replications to situations in which previous difficulties in situation awareness had been experienced would have been very informative as to whether the system is effective enough to pass to full-rate production.
|
From page 199... ...
SUMMARY The role of operational testing as a confirmatory exercise evaluating a mature system design has not been realized for IBCT/Stryker. This does not necessarily mean that the IOT should be postponed, since the decision to go to operational testing is based on a number of additional considerations.
|
From page 200... ...
4. Because it is not yet clear that the test design and the subsequent test analysis have been linked, ATEC should prepare a straw man test evaluation report in advance of test design, as recommended in the panel's October 2002 letter to ATEC (see Appendix A)
|
From page 201... ...
1992 Casualty Fractions and Casualty Exchange Ratio. Unpublished memorandum to J
|
From page 202... ...
2002a Interim Armored Vehicle IOTE: Test Design Review with NAS Panel. Unpublished presentation, Nancy Dunn and Bruce Grigg, April 15.
|
From page 203... ...
Appendix A Letter Report of the Pane! to the Army Test and Evaluation Command
|
From page 205... ...
whether the current operational test design is consistent with state-of-the-art methods in statistical experimental design; and (3) the applicability of models for combining information from testing and field use of related systems and from developmental test results for the Stryker with operational test results for the Stryker.
|
From page 206... ...
whether the current operational test design is consistent with state-of-the-art methods .
|
From page 207... ...
Preparation of this straw man TER will help ATEC assess those issues that cannot be informed by the operational tests as currently planned, will expose areas for which needed data is lacking, and will allow appropriate revision of the current operational test plan. The current test design calls for the execution of the IBCT/Stryker vs.
|
From page 208... ...
208 IMPROVED OPERATIONAL TESTING AND EVALUATION Bring to you the recommendations in this brief letter in a timely fashion will encourage ATEC to begin drafting a straw man Test Evaluation Report in time to influence operational test activities and to implement the change in test plan to allow the compared forces to undergo testing in the same season. Sincerely yours, Stephen Pollock, Chair Panel on Operational Test Design and Evaluation of the Interim Armored Vehicle
|
From page 209... ...
that: · the probability of an attacker victory1 is related to a variable called the "defenders advantage" or ADS, where ADVis a function of force strengths and final survivors; and · ADV~ in (FER) Since N= threat forces and M= friendly coalition forces in our definition of the force exchange ratio (FER)
|
From page 210... ...
to indicate the degree to which force imbalance is reduced, but it is also a useful historical measure of a force's warfighting capability for mission success. FER AND "DECISIVE FORCE" Following the demise of the Soviet Union and Operation Desert Storm, the U.S.
|
From page 211... ...
PHASE I REPORTAPPENDIXB: FORCE EXCHANGE RATIO .12— REIN .10 — o it, .08— Ct tn .06— Ct ~ .04— . _ 211 \ \ \ 2 3 4 5 6 Force Exchange Ratio FIGURE B-2 Force exchange ratio/casualty relationship.
|
From page 212... ...
= .505 1.0 2.0 3.0 4.0 .846 .937 .968 .981 Force Exchange Ratio FIGURE B-3 Force exchange ratio and decisive warfighting capability. SOURCE: Adapted from Thompson (1992)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.