scholarly journals An upper-bound estimate for the accuracy of glacier volume–area scaling

2013 ◽  
Vol 7 (6) ◽  
pp. 1707-1720 ◽  
Author(s):  
D. Farinotti ◽  
M. Huss

Abstract. Volume–area scaling is the most popular method for estimating the ice volume of large glacier samples. Here, a series of resampling experiments based on different sets of synthetic data is presented in order to derive an upper-bound estimate (i.e. a level achieved only within ideal conditions) for its accuracy. For real-world applications, a lower accuracy has to be expected. We also quantify the maximum accuracy expected when scaling is used for determining the glacier volume change, and area change of a given glacier population. A comprehensive set of measured glacier areas, volumes, area and volume changes is evaluated to investigate the impact of real-world data quality on the so-assessed accuracies. For populations larger than a few thousand glaciers, the total ice volume can be recovered within 30% if all data currently available worldwide are used for estimating the scaling parameters. Assuming no systematic bias in ice volume measurements, their uncertainty is of secondary importance. Knowing the individual areas of a glacier sample for two points in time allows recovering the corresponding ice volume change within 40% for populations larger than a few hundred glaciers, both for steady-state and transient geometries. If ice volume changes can be estimated without bias, glacier area changes derived from volume–area scaling show similar uncertainties to those of the volume changes. This paper does not aim at making a final judgement on the suitability of volume–area scaling as such, but provides the means for assessing the accuracy expected from its application.

2013 ◽  
Vol 7 (3) ◽  
pp. 2293-2331 ◽  
Author(s):  
D. Farinotti ◽  
M. Huss

Abstract. Volume-area scaling is the most popular method for estimating the ice volume of large glacier samples. Here, a series of resampling experiments based on different sets of synthetic data are presented in order to derive an upper-bound estimate (i.e. a level achieved only with ideal conditions) for the accuracy of its application. We also quantify the maximum accuracy expected when scaling is used for determining the glacier volume change, and area change of a given glacier population. A comprehensive set of measured glacier areas, volumes, area and volume changes is evaluated to investigate the impact of real-world data quality on the so assessed accuracies. For populations larger than a few thousand glaciers, the total ice volume can be recovered within 30% if all measurements available worldwide are used for estimating the scaling coefficients. Assuming no systematic biases in ice volume measurements, their uncertainty is of secondary importance. Knowing the individual areas of a glacier sample for two points in time allows recovering the corresponding ice volume change within 40% for populations larger than a few hundred glaciers, both for steady-state and transient geometries. If ice volume changes can be estimated without bias, glacier area changes derived from volume-area scaling show similar uncertainties as for the volume changes. This paper does not aim at making a final judgement about the suitability of volume-area scaling, but provides the means for assessing the accuracy expected from its application.


2020 ◽  
Author(s):  
Yi-Chieh Huang ◽  
Kamhon Kan ◽  
Larry Y. Tzeng ◽  
Kili C. Wang

Knowing how small a violation of stochastic dominance rules would be accepted by most individuals is a prerequisite to applying almost stochastic dominance criteria. Unlike previous laboratory-experimental studies, this paper estimates an acceptable violation of stochastic dominance rules with 939,690 real world data observations on a choice of deductibles in automobile theft insurance. We find that, for all policyholders in the sample who optimally chose a low deductible, the upper bound estimate of the acceptable violation ratio is 0.0014, which is close to zero. On the other hand, considering that most decision makers, such as 99% (95%) of the policyholders in the sample, optimally chose the low deductible, the upper bound estimate of the acceptable violation ratio is 0.0405 (0.0732). Our results provide reference values for the acceptable violation ratio for applying almost stochastic dominance rules. This paper was accepted by Manel Baucells, decision analysis.


Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1455
Author(s):  
Sunny R. K. Singh ◽  
Sindhu J. Malapati ◽  
Rohit Kumar ◽  
Christopher Willner ◽  
Ding Wang

Background: The incidence of invasive melanoma is rising, and approval for the first immune checkpoint inhibitor (ICI) to treat metastatic melanoma occurred in 2011. We aim to describe the epidemiology and outcomes in recent years, sociodemographic factors associated with the presence of metastasis at diagnosis, and the real‐world impact of ICI approval on survival based on melanoma subtype and race. Methods: This is a retrospective analysis of the National Cancer Database (NCDB) from the years 2004–2015. The primary outcome was the overall survival of metastatic melanoma by subtype. Secondary outcomes included sociodemographic factors associated with the presence of metastasis at diagnosis and the impact of treatment facility type and ICI approval on the survival of metastatic melanoma. Results: Of the 419,773 invasive melanoma cases, 93.80% were cutaneous, and 4.92% were metastatic at presentation. The odds of presenting with metastatic disease were higher in African Americans (AA) compared to Caucasians (OR 2.37; 95% CI 2.11–2.66, p < 0.001). Treatment of metastatic melanoma at an academic/research facility was associated with lower mortality versus community cancer programs (OR 0.75, 95 % CI 0.69–0.81, p-value<0.001). Improvement in survival of metastatic melanoma was noted for Caucasians after the introduction of ICI (adjusted HR 0.80, 95% CI 0.78–0.83, p < 0.001); however, this was not statistically significant for AA (adjusted HR 0.80, 95% CI 0.62–1.02, p‐value = 0.073) or ocular cases (HR 1.03, 95% CI 0.81–1.31, p‐value 0.797). Conclusion: Real‐world data suggest a 20% improvement in survival of metastatic melanoma since the introduction of ICI. The disproportionately high odds of metastatic disease at presentation in AA patients with melanoma suggest the need for a better understanding of the disease and improvement in care delivery.


2021 ◽  
Vol 161 ◽  
pp. S608
Author(s):  
I. Fornacon-Wood ◽  
H. Mistry ◽  
C. Johnson-Hart ◽  
J.P.B. O’Connor ◽  
C. Faivre-Finn ◽  
...  

2021 ◽  
pp. 146808742110387
Author(s):  
Stylianos Doulgeris ◽  
Zisimos Toumasatos ◽  
Maria Vittoria Prati ◽  
Carlo Beatrice ◽  
Zissis Samaras

Vehicles’ powertrain electrification is one of the key measures adopted by manufacturers in order to develop low emissions vehicles and reduce the CO2 emissions from passenger cars. High complexity of electrified powertrains increases the demand of cost-effective tools that can be used during the design of such powertrain architectures. Objective of the study is the proposal of a series of real-world velocity profiles that can be used during virtual design. To that aim, using three state of the art plug-in hybrid vehicles, a combined experimental, and simulation approach is followed to derive generic real-world cycles that can be used for the evaluation of the overall energy efficiency of electrified powertrains. The vehicles were tested under standard real driving emissions routes, real-world routes with reversed order (compared to a standard real driving emissions route) of urban, rural, motorway, and routes with high slope variation. To enhance the experimental activities, additional virtual mission profiles simulated using vehicle simulation models. Outcome of the study consists of specific driving cycles, designed based on standard real-world route, and a methodology for real-world data analysis and evaluation, along with the results from the assessment of the impact of different operational parameters on the total electrified powertrain.


2017 ◽  
Vol 33 (S1) ◽  
pp. 149-150
Author(s):  
Amr Makady ◽  
Ard van Veelen ◽  
Anthonius de Boer ◽  
Hans Hillege ◽  
Olaf Klunger ◽  
...  

INTRODUCTION:Reimbursement decisions are usually based on evidence from randomized controlled trials (RCT) with high internal validity but lower external validity. Real-World Data (RWD) may provide complimentary evidence for relative effectiveness assessments (REA's) and cost-effectiveness assessments (CEA's) of treatments. This study explores to which extent RWD is incorporated in REA's and CEA's of drugs used to treat metastatic melanoma (MM) by five Health Technology Assessment (HTA) agencies.METHODS:Dossiers for MM drugs published between 1 January 2011 and 31 December 2016 were retrieved for HTA agencies in five countries: the United Kingdom (NICE), Scotland (SMC), France (HAS), Germany (IQWiG) and the Netherlands (ZIN). A standardized data-extraction form was used to extract data on RWD mentioned in the assessment and its impact on appraisal (for example, positive, negative, neutral or unknown) for both REA and CEA.RESULTS:In total, fourty-nine dossiers were retrieved: NICE = 10, SMC = 13, IQWiG = 16, HAS = 8 and ZIN = 2. Nine dossiers (18.4 percent) included RWD in REA's for several parameters: to describe effectiveness (n = 5) and/or the safety (n = 2) of the drug, and/or the prevalence of MM (n = 4). CEA's were included in 25/49 dossiers (IQWiG and HAS did not perform CEA's). Of the twenty-five CEA's, twenty (80 percent) included RWD to extrapolate long-term effectiveness (n = 19), and/or identify costs associated with treatments (n = 7). When RWD was included in REA's (n = 9), its impact on the appraisal was negative (n = 4), neutral (n = 2), unknown (n = 1) or was not discussed in the appraisal (n = 2). When RWD was included in CEA's (n = 11), its impact on the appraisal varied between positive (n = 2), negative (n = 5) and unknown (n = 4).CONCLUSIONS:Generally, RWD is more often included in CEA's than REA's (80 percent versus 18.4 percent, respectively). When included, RWD was mostly used to describe the effectiveness of the drug (REA) or to predict long-term effectiveness (CEA). The impact of RWD on the appraisal varied greatly within both REA's and CEA's.


2020 ◽  
Vol 41 (Supplement_1) ◽  
pp. S115-S115
Author(s):  
James H Holmes ◽  
Stacey Kowal ◽  
Cheryl P Ferrufino

Abstract Introduction Treatment pathways in burn care are typically determined based on burn center (BC) and patient characteristics, although decisions may be influenced by anecdotal experience, personal preference, and hospital policies/purchasing decisions. Health economic (HE) evaluations can support improved decision-making, identifying the most cost-effective interventions for tailored care. A novel burn care model (BEACON) was developed with burn surgeons over several years and validated through numerous publications, including an assessment of the HE impacts of autologous skin cell suspension (ASCS) use for definitive burn closure. To ensure that BEACON accurately represents the current state of care, it is vital to update data that underpins model projections. This study collected real world data on practice patterns and patient outcomes for the most commonly seen burns (TBSA ≤ 20%) to update the current understanding of standard of care (SOC) costs and outcomes and to refine estimates on the impact of ASCS use in TBSA ≤ 20% patients. Methods Data was collected from a 10% sample of BCs, including: BC and patient characteristics, resource use, inpatient costs, and length of stay (LOS). NBR based inputs in BEACON were updated to reflect survey data for patients with TBSA ≤ 20%, with the ability to view data as a national aggregate sample and across BC characteristics. BEACON estimates patient and BC costs and outcomes across a spectrum of patient profiles (age, gender, inhalation injury, comorbidity status, burn depth, TBSA) and combines information on each patient profile to understand annual budget impact. Key outcomes were compared across the survey sample and published NBR trends. Using the updated BEACON, the BC budget impact of ASCS in burns TBSA ≤ 20% was assessed. Results The survey was collected from 16+ BCs, focusing on inpatient encounters in 2018. LOS was lower than NBR estimates, with some centers reporting LOS per %TBSA far below 1 d/%TBSA. Using the detailed bottom-up estimation of cost from BEACON with survey data, trends suggest total hospital costs for SOC are lower than published NBR charges given shorter LOS and updated cost and resource use assumption. Conclusions Compared to NBR 8.0, contemporary data suggests that fewer small TBSA burns are being treated in the inpatient setting; those treated have a LOS below NBR estimates. When using real world data, the impact of ASCS use in burns TBSA ≤ 20% was still calculated to be cost saving to a BC overall, given reductions in LOS and number of definitive closure procedures. Incorporating ASCS into appropriate TBSA ≤ 20% procedures can still result in a positive financial impact for BCs. Applicability of Research to Practice


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