Qualitative Sensitivity Analysis Research Articles

Towards a methodology for cluster searching to provide conceptual and contextual “richness” for systematic reviews of complex interventions: case study (CLUSTER)

BackgroundSystematic review methodologies can be harnessed to help researchers to understand and explain how complex interventions may work. Typically, when reviewing complex interventions, a review team will seek to understand the theories that underpin an intervention and the specific context for that intervention. A single published report from a research project does not typically contain this required level of detail. A review team may find it more useful to examine a “study cluster”; a group of related papers that explore and explain various features of a single project and thus supply necessary detail relating to theory and/or context.We sought to conduct a preliminary investigation, from a single case study review, of techniques required to identify a cluster of related research reports, to document the yield from such methods, and to outline a systematic methodology for cluster searching.MethodsIn a systematic review of community engagement we identified a relevant project – the Gay Men’s Task Force. From a single “key pearl citation” we conducted a series of related searches to find contextually or theoretically proximate documents. We followed up Citations, traced Lead authors, identified Unpublished materials, searched Google Scholar, tracked Theories, undertook ancestry searching for Early examples and followed up Related projects (embodied in the CLUSTER mnemonic).ResultsOur structured, formalised procedure for cluster searching identified useful reports that are not typically identified from topic-based searches on bibliographic databases. Items previously rejected by an initial sift were subsequently found to inform our understanding of underpinning theory (for example Diffusion of Innovations Theory), context or both. Relevant material included book chapters, a Web-based process evaluation, and peer reviewed reports of projects sharing a common ancestry. We used these reports to understand the context for the intervention and to explore explanations for its relative lack of success. Additional data helped us to challenge simplistic assumptions on the homogeneity of the target population.ConclusionsA single case study suggests the potential utility of cluster searching, particularly for reviews that depend on an understanding of context, e.g. realist synthesis. The methodology is transparent, explicit and reproducible. There is no reason to believe that cluster searching is not generalizable to other review topics. Further research should examine the contribution of the methodology beyond improved yield, to the final synthesis and interpretation, possibly by utilizing qualitative sensitivity analysis.

Assessing parameter importance of the Common Land Model based on qualitative and quantitative sensitivity analysis

Abstract. Proper specification of model parameters is critical to the performance of land surface models (LSMs). Due to high dimensionality and parameter interaction, estimating parameters of an LSM is a challenging task. Sensitivity analysis (SA) is a tool that can screen out the most influential parameters on model outputs. In this study, we conducted parameter screening for six output fluxes for the Common Land Model: sensible heat, latent heat, upward longwave radiation, net radiation, soil temperature and soil moisture. A total of 40 adjustable parameters were considered. Five qualitative SA methods, including local, sum-of-trees, multivariate adaptive regression splines, delta test and Morris methods, were compared. The proper sampling design and sufficient sample size necessary to effectively screen out the sensitive parameters were examined. We found that there are 2–8 sensitive parameters, depending on the output type, and about 400 samples are adequate to reliably identify the most sensitive parameters. We also employed a revised Sobol' sensitivity method to quantify the importance of all parameters. The total effects of the parameters were used to assess the contribution of each parameter to the total variances of the model outputs. The results confirmed that global SA methods can generally identify the most sensitive parameters effectively, while local SA methods result in type I errors (i.e., sensitive parameters labeled as insensitive) or type II errors (i.e., insensitive parameters labeled as sensitive). Finally, we evaluated and confirmed the screening results for their consistency with the physical interpretation of the model parameters.

Sensitivity quantification of jointed plain concrete pavement mechanistic-empirical performance predictions

This paper focuses on quantitative and qualitative sensitivity analyses of various jointed plain concrete pavement (JPCP) mechanistic-empirical design scenarios. Two base cases of JPCP types were utilized: (1) new construction on granular base (new JPCP case), and (2) both new construction/reconstruction on stabilized foundations or rehabilitation on underlying asphalt/concrete layers (JPCP over stiff foundation case). Each base case was designed for three traffic levels in five climate zones to evaluate the sensitivity of predicted distresses using the American Association of State Highway and Transportation Officials (AASHTOs) mechanistic-empirical pavement design guide (MEPDG) procedure. Sensitivity is characterized by a design limit normalized sensitivity index (NSI), which can be interpreted as the percentage change in predicted distress relative to the design limit caused by a given percentage change in the design input. For JPCP types and distresses, the sensitivities of the design inputs for the Portland cement concrete (PCC) surface layer were the most important. The findings suggests that more caution is required to select PCC slab design features and PCC material properties in JPCP design using MEPDG and DARWin-ME™ for designing cost-effective and sustainable concrete pavements.

Cost-effectiveness of nutritional intervention on healing of pressure ulcers

Pressure ulcers not only affect quality of life among the elderly, but also bring a large economic burden. There is limited evidence available for the effectiveness of nutritional interventions for treatment of pressure ulcers. In Japan, recently, a 60-patient randomized controlled trial of nutritional intervention on pressure ulcers demonstrated improvement in healing of pressure ulcers, compared with conventional management. To evaluate value for money of nutritional intervention on healing of pressure ulcers, cost-effective analysis was carried out using these trial results. The analysis was carried out from a societal perspective. As effectiveness measures, pressure ulcer days (PUDs) and quality-adjusted life years (QALYs) were estimated. Prevalence of pressure ulcers was estimated by the Kaplan-Meier method. Utility score for pressure ulcers is derived from a cross-sectional survey among health professionals related to pressure ulcers. Costs (e.g., nutritional interventions and management of pressure ulcers) were estimated from trial data during observation and follow-up. Stochastic and qualitative sensitivity analyses were performed to examine the robustness of results. For observation (12 weeks) and follow-up (12-week observation plus 4-week follow-up), nutritional intervention reduced PUDs by 9.6 and 16.2 per person, and gained 0.226×10(-2) QALYs and 0.382×10(-2) QALYs per person, respectively. In addition, costs were reduced by $542 and $881 per person, respectively. This means nutritional intervention is dominant (cost savings and greater effectiveness). The sensitivity analyses showed the robustness of these results. Economic evaluation of nutritional intervention on healing pressure ulcers from a small randomized controlled trial showed that this intervention is cost saving with health improvement. Further studies are required to determine whether this is a cost-effective intervention for widespreaduse.

Study of Colonial Manuscripts from San Nicolás Coatepec, México, Through UV&IR Imaging and XRF

ABSTRACTThe necessity of studying cultural heritage through non-invasive and non-destructive techniques has led to significant advances in the last decade. One of the most recent advancements in this theme in Mexico is the portable X-ray system SANDRA, which was used to study three manuscripts directly related to the history of “San Nicolás Coatepec”, Mexico. X-ray fluorescence was chosen as the suitable technique because it can provide a fast qualitative and quantitative multielemental high sensitivity analysis. The documents were examined globally, using imaging techniques with UV and IR lighting. This research evinced a change in the composition and evolution of writing materials (inks and pigments) and provided information concerning historical use of the documents and its actual legal value as a property document. It also stressed the need of spanning these results to an extensive research attaining other regions of Mexico, in order to fully understand the Mexican documents particularities, aging and deterioration. This, in turn, will provide not only historical material information but also an invaluable scoop to understand deterioration and conservation issues.

Association Between Type of Health Insurance and Elective Cesarean Deliveries: New Jersey, 2004–2007

I examined the relationship between insurance coverage, which may influence physician incentives and maternal choices, and cesarean delivery before labor. I analyzed hospital discharge data for mothers without previous cesarean deliveries in New Jersey between 2004 and 2007, with adjustment for maternal age, race, marital status, and maternal, fetal, and placental conditions. Nearly 1 in 7 women (13.9%) had a cesarean delivery without laboring. Insurance status was strongly associated with cesarean birth. Women insured by Medicaid (adjusted relative risk [ARR] = 0.88; 95% confidence interval [CI] = 0.84, 0.91) or self-paying (ARR = 0.81; 95% CI = 0.78, 0.85) had a significantly lower likelihood, and women insured by BlueCross (ARR = 1.06; 95% CI = 1.03, 1.09) or standard commercial plans (ARR = 1.06; 95% CI = 1.02, 1.10) had a significantly higher likelihood of cesarean delivery than did women insured by commercial health maintenance organizations. These associations persisted in subsets restricted to lower-risk women and in qualitative sensitivity analyses for a hypothetical single, binary, unmeasured confounder. Insurance status has a small, independent impact on whether a woman without a previous cesarean delivery proceeds to labor or has a cesarean delivery without labor.

Evidences of International Financial Reporting Standards (IFRS) Implementation in Brazil: The Case of Derivatives

The objective of this paper is to analyze the implementation of International Financial Reporting Standards (IFRS) in Brazil. This analysis focuses specifically on derivative transactions. For these, a disclosure index has been elaborated using recent Brazilian standards, which are based on the IAS 39 – Financial Instruments Recognition and Measurement and on the IAS 32 – Financial Instruments: Disclosure and Presentation. This disclosure index has a total of 4 categories and 22 sub-categories: qualitative information (5), quantitative information (6), derivative values (5) and sensitivity analysis (6). Sample is composed by the top 100 largest non-financial public companies. Information has been gathered from Financial Statements for the years ended in 2006, 2007 and 2008 with the use of content analysis. Main findings are: (i) more than half of companies did not disclose the initial accounting effects of new standards, (ii) the majority of companies did disclose the fair value of these financial instruments but did not disclose the criterion utilized in computing them and (iii) some companies still do not evidence any information regarding their transaction with derivatives. In sum, new accounting standards, based on IFRS, did have a positive impact of corporate disclosure but companies still do not disclose all the information required.

Monotonicity properties of wholesale price contracts

This paper contributes to the supply chain contracts literature in economics and operations by performing qualitative sensitivity analysis of a wholesale price contract in a two-echelon supply chain setting. Order-theory tools are used to derive sufficient conditions for monotonicity of contract parameters. The upstream supplier is modeled as a Stackelberg leader. The supplier is assumed to have complete information about the costs and revenue function of the downstream retailer. It is shown that an equilibrium wholesale price weakly increases with an increase in the supplier production cost rate, but it may increase or decrease with an increase in the retailer cost rate. As either the supplier production cost or the retailer cost increases, the supplier profit decreases weakly. Additional sensitivity analysis is performed assuming certain properties of the retailer revenue function. Several well-known results in the supply chain contracting literature can be considered as special cases of the more general theorems developed here. In particular, this paper reexamines the analysis of a newsvendor supply chain problem by Lariviere and Porteus [Lariviere, M.A., Porteus, E.L., 2001. Selling to the newsvendor: An analysis of price-only contracts. Manufacturing & Service Operations Management 3, 293–305]. This paper generalizes and extends their work, by establishing properties of the newsvendor demand distribution that guarantee monotonicity of the contract parameters, without requiring a unique contract solution.

Sensitivity Analysis in Computable General Equilibrium Models: An Application for the Regional Effects of the Free Trade Area of the Americas (FTAA)

The goal of this paper is to explore an applied tool for sensitivity analysis in computable general equilibrium models (CGE). An interregional CGE model is used to assess the impacts of the Free Trade Area of the Americas (FTAA) on Brazilian regions. As interregional substitution and factor mobility can be the key mechanisms that drive the model results, one should take closer attention to the estimated regional trade elasticities. Since information for proper estimation is rarely available, qualitative sensitivity analysis should be designed and used together with systematic quantitative sensitivity analysis. The sensitivity of results to parameters is evaluated in such a way that we can assess the robustness of results to different levels of elasticities of substitution

Cost Considerations in Optimal Capacity Acquisition: An Option Pricing Approach

The optimal capacity choice is a tradeoff between the costs of shortage and excess capacity. This paper models the costs as the prices of an infinite number of European call and put options maturing continuously over the planning horizon. This approach allows a firm to consider the benefits of flexibility arising from delaying the acquisition of some capacity to a later time when more information about stochastic demand becomes available. The firm can then adjust the capacity to meet exact demand by purchasing in the spot market or reselling in the salvage market. The model determines optimal capacity by minimizing acquisition and capacity adjustment costs. I compare the model to extant models and discuss some special situations. Qualitative sensitivity analysis describes the impact of changes in model parameters on the optimal capacity. A Monte Carlo simulation compares this model with other models and results show that the Option Pricing model results in the lowest operating cost for all scenarios considered. A substantially simplified version of the model, which does not require complete understanding of option pricing methods, also performs well under certain conditions.

Alternative foreign exchange management protocols: an application of sensitivity analysis

This paper considers the choice between two foreign exchange management protocols, namely whether to hold currencies received until required, or whether to convert foreign currencies into the home reporting currency and back as needed. The alternative protocols involve a tradeoff between saving transaction costs versus stability of home currency values and economies of scale in interest earned on working capital balances. Qualitative sensitivity analysis is applied to the currency management problem in this form to investigate sensitivities and interdependencies in sources of and needs for currencies. The analysis reveals several implications which are not apparent without viewing the problem in such a context.

Qualitative Sensitivity Analysis in Monotropic Programming

Optimal selections are parameter-dependent optimal solutions of parametric optimization problems whose properties can be used in sensitivity analysis. Here we present a qualitative theory of sensitivity analysis for linearly-constrained convex separable (i.e., monotropic) parametric optimization problems. Three qualitative sensitivity analysis results previously derived for network flows are extended to monotropic problems: The Ripple and Smoothing Theorems give upper bounds on the magnitude of optimal-variable variations as a function of variations in the problem parameter(s), the theory of substitutes and complements provides necessary and sufficient conditions for optimal-variable changes to consistently have the same (or the opposite) sign(s) in two given variables, and the Monotonicity Theorem links changes in the value of the parameters to changes in optimal decision variables. We introduce a class of optimal selections for which these results hold, thereby answering a long-standing question due to Granot and Veinott (1985) with a simple and elegant method. Although a number of results are known to depend on the resolution of NP-complete problems, easily computable nonnetwork classes of monotropic problems such as unimodular systems of constraints emerge in the light of the present approach.

Optimization and Evaluation of Single‐Staged Transportation Systems Example for the Solution of Highly Complex Technical Problems

ABSTRACTSpace transportation vehicles are an example for highly complex technical systems. The optimization of these systems is very difficult due to the high degree of complexity and connectivity between the system elements and between the vehicle and its environment. Single Stage to Orbit (SSTO) vehicles as potential transportation systems for future space activities have not yet been investigated in sufficient depth to get an entirely consistent overview of potential fields of operation.A systems engineering approach has been considered to systematically examine the influence of system variations on the overall performance and cost of the vehicle. To speak more generally, in the early pre‐design phase of a new system it seems to be reasonable to first elaborate some alternative concepts. In a second step qualitative sensitivity analyses based upon slight variations of certain vehicle components are investigated.The proposed process has proven to be a very useful and reasonable approach for relatively detailed and reliable evaluation and optimization of complex systems in the pre‐design phase.

Ripples, complements, and substitutes in generalized networks

We extend the qualitative theory of sensitivity analysis for minimum-cost pure network flows of Granot and Veinott [17] to generalized network flow problems, that is, network flow problems where the amount of flow picked up by an arc is multiplied by a (positive) gain while traversing the arc. Three main results are presented. The ripple theorem gives upper bounds on the absolute value of optimal-flow variations as a function of variations in the problem parameter(s). The theory of substitutes and complements provides necessary and sufficient conditions for optimal-flow changes to consistently have the same (or the opposite) sign(s) in two given arcs, whereas the monotonicity theorem links changes in the value of the parameters to changes in optimal arc flows. Bounds on the rates of changes are also discussed. Compared with pure networks, the presence of gains makes qualitative sensitivity analysis here a much harder task. We show the profound effect on computational issues caused by the departure from the pure network structure.

Automatic Diagnostic Rule Generation for Rule-Based Controllers by Qualitative Sensitivity Analysis

Automatic Diagnostic Rule Generation for Rule-Based Controllers by Qualitative Sensitivity Analysis

Feasible and optimal retrofitting of batch‐soluble to continuous‐immobilized enzyme processes applied to adsorbed enzymes

The advantages of retrofitting an in situ soluble enzyme batch process to an immobilized enzyme continuous process are contrasted against the disadvantages by means of a dimensionless feasibility/optimization analysis. The general analysis is applied to the case of an adsorbed enzyme system where a maximum in activity occurs with respect to loading. For this case, a minimum in the ratio of enzyme-carrier complex working lifetime to in situ batch process time and a maximum in the cost difference between the in situ and retrofit processes occurs with respect to loading and retrofit process conversion. For the maximization of cost difference, the analysis also suggests a criterion that can be used to determine whether the values for optimal loading and retrofit conversion will result in the retrofit being economically feasible. When infeasibility occurs, qualitative sensitivity analysis for a variety of situations points out whether a catalyst or process modification will improve feasibility the most. Apart from forming the basis for an iterative retrofit process design algorithm, the modeling approach's ability to specify optimal values of catalyst properties such as loading lends itself to defining process-specific, catalyst design "targets" would be useful for those developing immobilized enzyme preparation methodology and those investigating enzyme-carrier interactions.

Qualitative Problems in Matrix Theory

Qualitative Problems in Matrix Theory