Efficient Ranking Research Articles

Evaluating the joint efficiency of German trade forecasts - a nonparametric multivariate approach

ABSTRACT I analyse the joint efficiency of export and import forecasts by leading economic research institutes for the years 1970 to 2017 for Germany in a multivariate setting. To this end, I compute, in a first step, multivariate random forests in order to model links between forecast errors and a forecaster’s information set, consisting of several trade and other macroeconomic predictor variables. I use the Mahalanobis distance as performance criterion and, in a second step, permutation tests to check whether the Mahalanobis distance between the predicted forecast errors for the trade forecasts and actual forecast errors is significantly smaller than under the null hypothesis of forecast efficiency. I find evidence for joint forecast inefficiency for two forecasters, however, for one forecaster I cannot reject joint forecast efficiency. For the other forecasters, joint forecast efficiency depends on the examined forecast horizon. I find evidence that real macroeconomic variables as opposed to trade variables are inefficiently included in the analysed trade forecasts. Finally, I compile a joint efficiency ranking of the forecasters.

Rank adaptive tensor recovery based model reduction for partial differential equations with high-dimensional random inputs

This work proposes a systematic model reduction approach based on rank adaptive tensor recovery for partial differential equation (PDE) models with high-dimensional random parameters. Since the standard outputs of interest of these models are discrete solutions on given physical grids which are high-dimensional, we use kernel principal component analysis to construct stochastic collocation approximations in reduced dimensional spaces of the outputs. To address the issue of high-dimensional random inputs, we develop a new efficient rank adaptive tensor recovery approach to compute the collocation coefficients. Novel efficient initialization strategies for non-convex optimization problems involved in tensor recovery are also developed in this work. We present a general mathematical framework of our overall model reduction approach, analyze its stability, and demonstrate its efficiency with numerical experiments.

Allocating a fixed cost across decision making units with explicitly considering efficiency rankings

Fixed cost allocation (FCA) is one of the most important applications of the data envelopment analysis (DEA). Numerous studies on this problem have appeared in the literature in the last two decades; however, almost all of them are based on either efficiency invariance or efficiency maximization, both of which focus mainly on efficiency scores. It is notable that the efficiency score is more an intermediate indicator and the corresponding efficiency ranking is actually the main focus. Motivated by this observation, this paper aims to propose a new approach for allocating the fixed cost across decision making units (DMUs) based on efficiency ranking. To this end, the efficiency ranking intervals are explicitly determined by taking allocated costs and feasible weights into account. The results indicate that each DMU can be ranked at any position ranging from the best one to the worst n, and there are fixed cost allocation schemes that can determine the best efficiency ranking of one for each individual DMU simultaneously under a set of common weights. Furthermore, we define a new comprehensive satisfaction degree based on the interval of the upper and lower bounds of the allocated costs. Then, we generate the final allocation scheme using an iterative procedure to maximize the satisfaction degree across all DMUs. Finally, the proposed approach is applied to a classic numerical example from prior literature and an empirical study from the real world to illustrate its usefulness and efficacy.

Efficiency evaluation of a sustainable hydrogen production scheme based on super efficiency SBM model

The hydrogen production transition from coal to renewable energy is key to realize low-carbon in the whole hydrogen energy system. To accelerate the transition, this study proposes a sustainable hydrogen production scheme combining coal-based hydrogen production with renewable hydrogen production. Specifically, the excess alkalinity generated by water electrolysis can capture the CO2 from coal-based hydrogen production. Additionally, the oxygen generated by water electrolysis can be provided for coal-based hydrogen production. Different from previous studies, we use the super efficiency SBM model with undesirable outputs to calculate the efficiency of coal-based hydrogen production, renewable hydrogen production and the integrated scheme. Results show that the efficiency of the integrated scheme with the reasonable configuration is 2.01. And it has the highest efficiency ranking, followed by coal-based hydrogen production and hydrogen production from wind energy, which are 1.07 and 0.84, respectively. On the other hand, the hydrogen production from solar energy is 0.32, which has the lowest ranking. Therefore, the integrated scheme can provide the low-carbon hydrogen by the inexpensive cost. Popularizing the integrated scheme should promote the large-scale of renewable hydrogen production, thereby guiding the green transformation of hydrogen production.

Improving manufacturing cycle efficiency through new multiple criteria data envelopment analysis models: an application in green and lean manufacturing processes

The Green & Lean Manufacturing organisational strategy emphasises waste and environmental impact reduction, efficiency increase, quality improvement, and cycle time reduction by eliminating non-value-added activities. Usually, companies adopt the Manufacturing Cycle Efficiency indicator to identify and make improvements to meet Lean Manufacturing requirements. This work proposes an innovative approach based on Multiple Criteria Data Envelopment Analysis to calculate a new indicator, hereby called Value-Added Activities in Manufacturing Processes, to measure the efficiency of productive processes through Green Manufacturing concepts. This new indicator was applied in a company with the purpose of validating and testing it. The Levene’s test was used to statistically validate the proposed procedure. As an immediate advantage of this new indicator, it was possible for managers to insert more information, such as incorporating aspects associated with Green Manufacturing, in the calculation of the Manufacturing Cycle Efficiency, making it more consistent and representative of what is happening in practice. Among this additional piece of information on the real processes analysed, it is worth mentioning, for example, the volume of scrap generated, the amount of sales invoicing, the quantity of work in process, and the quantity of finished products in stock. Specialists in Green & Lean Manufacturing, managers of the studied company, validated the results of the new indicator because they observed greater adherence to the practice of these new calculated values, when compared to the traditionally adopted calculations. Also highlighted, are other advantages of the new indicator such as the establishment of an efficiency ranking between the productive processes analysed and the determination of feasible goals to turn processes identified as inefficient into efficient ones.

Size Versus Efficiency: A Case Study of US Commercial Carriers

As the demand for transportation with commercial aviation increases, each single day an airline will adjust their routes and services according to this demand. The main purpose of an airline is to increase the Shareholder Value Added (SVA) in their financial statements. Increasing the SVA value depends on high efficiency in daily flight operations. In this captioned paper, we researched five major airlines in US market American, Delta, United, Hawaiian, Jet Blue and Alaska airlines regarding to their efficiencies.The data regarding 2012 - 2016 years for ten different airline variables were obtained from Diio Mi© software. After obtaining the data, the raw data was normalized. After, the efficiency of each airline for each selected year was calculated by Data Envelopment Analysis (DEA) in Lindo© optimization software. In the Conclusion, the efficiencies of all airlines were ranked according to calculated efficiency scores.According to results, the efficiency of the airlines was relatively stable over the study time period and the airline with the most extensive fleet is in the lowest position in the efficiency ranking. We speculate based on the study results that one possible reason we obtained similar results for each year is that all the airlines in the study are major airlines and are competitors that benchmark each other in terms of efficiency and results with industrial optimization tools.

基于数据包络分析方法的城市水资源利用效率研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于数据包络分析方法的城市水资源利用效率研究 DOI: 10.5846/stxb201903020385 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院前沿项目（QYZDY-SSW-DQC004）；北京市科技计划项目（Z171100004417025）；广东省省级科技计划项目（2016B02024007） Efficiency assessment of water resource utilization cities based on data envelopment analysis Author: Affiliation: Fund Project: Frontier Project of Chinese Academy of Sciences (QYZDY-SSW-DQC004); Beijing Science and Technology Plan Project (Z171100004417025); Guangdong Provincial Science and Technology Plan Project (2016B02024007) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了对我国城市水资源利用效率问题进行分析和评价，本文基于数据包络分析方法，从农业、工业、生活、社会等几个方面共选取了5个输入指标及6个输出指标，利用AIC信息准则（Akaike information criterion）进行了变量选择，构建了较为科学合理的用水效率评价指标体系.在此基础上，采用香农熵指数提升了传统CCR（由Charnes A，Cooper W W，Rhodes E提出）模型的识别能力，选取我国31个省会城市为研究对象，给出了省会城市水资源效率的完整排名。结果表明：①绝大部分城市综合效率得分（CES，Comprehensive efficiency score）普遍不高，投入产出比仍有较大的进步空间；②拉萨、北京、天津、银川、海口、上海等城市CES得分相对较高，这说明一个城市水资源利用效率的高低与经济发展水平可能没有必然的联系，其他城市应结合自身情况向CES得分靠前的城市进行学习；③重庆、南宁、南昌、长沙等水资源较丰富的城市CES得分反而较低，表明这些城市可能存在大量水资源被浪费，应建立起节水机制，同时优化产业结构。 Abstract:Improving efficiency of water resources utilization is the key to alleviate the contradiction between water supply and demand while achieving sustainable economic and social development. In order to analyze and evaluate the water consumption efficiency of the provincial capital cities in China, this paper selected five input indicators and six output indicators from agriculture, industry, life and society based on data envelopment analysis method. Then we used Akaike Information Criterion (AIC) for variable selection and constructed a scientific and rational water-use efficiency indicator system. On this basis, the Shannon Entropy Index is used to enhance the recognition ability of the traditional CCR model, and the complete ranking of water resources efficiency in the provincial capitals is given. The results show that (1) the comprehensive efficiency scores (CES) of most cities are not high. Their input-output ratio still has a lot of room for improvement. (2) The scores of CES in Lasa, Beijing, Tianjin, Yinchuan, Haikou, Shanghai etc. are relatively high, which indicate that there may be no necessary connection between the level of water use efficiency of a city and the level of economic development. At the same time, other cities should combine their own conditions to learn from cities with higher scores in CES. (3) Cities such as Chongqing, Nanning, Nanchang, and Changsha are rich in water resources, but the CES is not ideal. This shows that a large amount of water resources may be wasted and these cities should optimize their industrial structures while establishing a water-saving mechanism. In addition, due to the lack of variable selection system in most literatures and the inadequacy of traditional models in the ability of efficiency identification, this paper innovatively combined the AIC variable selection method, data envelopment analysis method, and Shannon Entropy Index method. The combination of the three methods can achieve the advantages and disadvantages of complementarity, not only fully consider a large number of input and output variables, make the analysis closer to reality, the variable indicator system obtained by the AIC criterion also perfectly conforms to the meaning of actual water resource utilization efficiency. 参考文献 相似文献 引证文献

Cost Containment of Total Knee Arthroplasty in the US: DEA Analysis on Regional Cost and Clinical Comparison between 2010 and 2013

The purpose of this research is to evaluate clinical and cost effectiveness of total knee replacement surgery (TKA) for adults hospitalized in the United States between 2010 and 2013. We tried to answer the question that whether lower length of stay and higher utilization of post-op facilities would be helpful to control the overall costs. Using the National Hospital Discharge Survey (NHDS) database and cost data from Blue Cross Blue shield, this study seeks to identify which U.S. region renders the highest quality patient care during a three-year span of 2008-2010. Using length of stay and discharge disposition (2010) as input factors, and regional TKA costs (2013) as output factors, Data Envelopment Analysis (DEA), a non-parametric method, illustrated the efficiency ranking of four regions in the US on TKA expenditures. The result shows the West is the most efficient region on controlling the overall cost by shrinking the length of stay and increasing the utilization of short-term/long-term care facilities.

Multiobjective Ecological Strategy Optimization for Two-Stage Disassembly Line Balancing With Constrained-Resource

Effective disassembly of obsolete products is critical for remanufacturing, recycling and recycling. However, existing disassembly studies have few or no resource constraints, such as limited numbers of disassembly operators and tools. Two-stage disassembly model is used to improve the flexibility to adapt to remanufacturing market demand. Based on existing references, this paper establishes a multiobjective two-stage disassembly model based on two-stage data envelopment analysis (two-stage DEA). The resource-constructed two-stage DEA model in this paper fully considers the dynamic configuration information of the output factors in each stage. To avoid the problem where the overall efficiency is optimal, the research constructs a resource constrained efficiency two-stage disassembly model. First, with the goal of minimum disassembly time, economy, energy consumption and environment, this study proposes eNSGA-II. By using mixed mutation and ecological evolution strategies, a well-distributed noninferior solution set is obtained. Second, the group of 16 disassembly schemes is used as decision-making units (DMU $s$ ) of the two-stage DEA. A comparison with Chen’s model rankings shows that the model in this paper performs better. DMU6 has the highest efficiency ranking, which is the best disassembly solution. Finally, the effectiveness of the proposed algorithm is verified by examples. Compared with NSGA-II and SPEA-II, eNSGA-II shows better performance and effectiveness.

Assertion Ranking Using RTL Source Code Analysis

We present a systematic and efficient ranking method to quantify the goodness of an assertion. We model dependencies among design variables as a directed graph called a variable dependency graph . We define assertion importance and assertion complexity metrics and use the dependency graph to algorithmically compute those two metrics. We repurpose an assertion coverage algorithm from the literature to form a statement-coverage-based ranking as our baseline. We compare our assertion ranking both qualitatively and quantitatively to this baseline. We demonstrate that our ranking is computationally more efficient than statement-coverage-based ranking and takes up to $4366\times $ less computation time. We identify the potential design intents that each ranking prioritizes. We also discuss at length the effect of those prioritizations on the rank agreement and the bug detection ability of the top-ranked assertions according to the two rankings. Finally, we provide a comprehensive ranking for a set of assertions by combining our ranking and the statement-coverage-based ranking.

Antioxidant activity assisted by modified particle surface in POSS/EPDM hybrids

The presented results prove the stabilization activity of modified POSS particles in the thermal and radiochemical degrading EPDM. Various mono- or di-substituents (-CH3, -OCH3, -F, -Cl) assist the delay of oxidative degradation by the electronic interactions of free radicals inside the free volume of polyhedral oligomeric silsequioxanes (POSS) with substituents placed on the outer particle surface. The stabilization of EPDM/modified POSS patterns is characterized by chemiluminescence, FTIR spectroscopy and thermogravimetric analysis. The concern of each formulation is individually defined by the accumulation of oxygen-containing configurations, which depicts the degree of conversion for free radicals into degradation products. The efficiency ranks of substituents based on the surface effects are conclusive in respect with POSS molecular compositions. The performance of protection against oxidation is evident on the high temperature range and the advanced exposure to the action of γ-radiation. Meanwhile the damaging effect of γ-irradiation on the inorganic phase is characterized by XRD and SEM assays.

China’s regional industrial two-stage system – Efficiencies and their influencing factors

To reduce waste discharge, China’s industrial system has been divided into stages of clean production (CP) and waste treatment (WT). Based on the conceptual framework of this industrial two-stage system, this study develops two network slacks-based measure models to evaluate the efficiency of this system from the perspectives of outside peers and inside managers. To identify the inefficient stages for each region during the period of 2011–2015, CP and WT efficiencies are further evaluated. Then, the factors influencing CP and WT efficiencies are explored using the censored least absolute deviations model. The results indicate that the industrial two-stage efficiencies of the external model are lower than those of the internal model, have more discriminatory power, and a similar efficiency rank. Moreover, CP efficiencies are higher than or equal to WT efficiencies for almost all regions. A higher economic development level significantly improved CP and WT efficiencies, while a higher industrial concentration degree significantly decreased these. Both influencing factors exerted a larger influence on WT efficiency than on CP efficiency. The strength of environmental protection did not significantly affect CP efficiency but exerted a positive effect on WT efficiency.

Cr diffusion coatings on a ferritic-martensitic steel for corrosion protection in KCl-rich biomass co-firing environments

Three diffusion coatings (Cr, Ni + Cr, Ni-P + Cr) on a ferritic-martensitic X20CrMoV12-1 steel were investigated in a biomass-co-firing atmosphere in comparison to uncoated austenitic DMV 310 N. Exposures were conducted at 650 °C for up to 300 h with pure sulphates as well as a mixture of sulphates and KCl. These aggressive testing conditions were chosen to accelerate degradation of the specimens allowing for an efficient ranking between them. Beneath the deposit of Na2SO4-K2SO4 the coatings proved to be highly resistant whereas addition of KCl drastically accelerated the corrosive attack. This is discussed within the frame of different synergistic high temperature corrosion mechanisms.

Stochastic analysis of the economic growth of OECD countries

This study examined the determinants of economic development for the 34 member countries of the Organization for Economic Cooperation and Development (OECD) and analysed efficient uses of economic development resource endowments. The methodology included econometric panel data modelling and stochastic frontier analysis, using the Cobb-Douglas production function and trans-logarithmic functional form to analyse data from 2003 to 2012. Economic growth was measured by the gross domestic product (GDP) of each economy. As a result, the determinants of economic development were presented and a ranking of efficiency was obtained for all OECD economies throughout the period of analysis. It was concluded that countries with higher economic growth levels have higher efficiency rankings. For example, countries with higher efficiency rankings were Luxembourg and the U.S.; Chile and Mexico were ranked lower. Finally, there was a positive relationship between growth levels and technical efficiency levels.

Efficiency of Polish seaports against the background of the largest ports in Europe

Seaport efficiency are the critical factors for handling of goods in the international supply chains and plays an important role in trade exchange with other countries. It is important to evaluate efficiency of seaports to reflect their status and reveal their position in competitive environment. The main purpose of this article is to use Data Envelopment Analysis to measure the technical efficiency of main seaports in Poland and main seaports in Europe. Data Envelopment Analysis enables one to assess how efficiently a Polish seaports uses the available inputs to generate a set of outputs relative to other units in the data set. The analysis gives a possibility to create an efficiency ranking of seaports.

Internalization Characterization of Si Nanorod with Camouflaged Cell Membrane Proteins Reveals ATXN2 as a Negative Regulator.

The fabrication of shape-controlled nanocarriers is critical for efficient delivery of biomolecules across the cell membrane. Surface coating of the nanocarrier can improve internalization efficiency. Here, we developed a facile method of silicon nanorod fabrication leading to a controlled size and shape. We then systematically evaluated five surface modifications with membrane proteins from different cancer cell lines including MCF7, MD231, Hela, Panc-PDX, and Panc-1. We demonstrated that silicon nanorods coated with either a homolytic or heterolytic membrane protein coating have significantly improved internalization efficiency as compared with uncoated Si nanorods. To elucidate the molecular mechanism of the improved efficiency associated with a modified coating, we analyzed the coating membrane proteins derived from five cell lines with proteomics and identified 601 proteins shared by different cell sources. These proteins may function as cell-substrate adhesion molecules that contribute to the enhanced internalization. We also tested the internalization efficiency of nanorods with different coatings in each of the five cell lines to determine the influencing factors from target cells. We found that the internalization efficiency varied among different target cells, and the ranking of the average efficiency was as follows: Hela > Panc-PDX > MD231 > MCF7 > Panc-1. The bioinformatics analysis suggested that the low internalization efficiency in Panc-1 cells might be associated with the upregulation of ATXN2, which is a negative regulator of endocytosis. We further demonstrated that ATXN2 knockdown with specific siRNA significantly improved nanorod internalization efficiency in Panc-1 cells suggesting that ATXN2 can be a reference for efficiency prediction of nanoparticle delivery to tumor cells. Thus, we studied the effect of different cancer cell membrane proteins on nanorod uptake efficiencies. These results can improve nanorod internalization to cancer cells, including a fundamental understanding of the internalization efficiency of cancer cells.

A Unified Approach to Efficiency Decomposition for a Two-Stage Network DEA Model with Application of Performance Evaluation in Banks and Sustainable Product Design

Data envelopment analysis (DEA) is a data-driven tool for performance evaluation, benchmarking and multiple-criteria decision-making. This article investigates efficiency decomposition in a two-stage network DEA model. Three major methods for efficiency decomposition have been proposed: uniform efficiency decomposition, Nash bargaining game decomposition, and priority decomposition. These models were developed on the basis of different assumptions that led to different efficiency decompositions and thus confusion among researchers. The current paper attempts to reconcile these differences by redefining the fairness of efficiency decomposition based on efficiency rank, and develops a rank-based model with two parameters. In our new rank-based model, these three efficiency decomposition methods can be treated as special cases where these parameters take special values. By showing the continuity of the Pareto front, we simplify the uniform efficiency decomposition, and indicate that the uniform efficiency decomposition and Nash bargaining game decomposition can converge to the same efficiency decomposition. To demonstrate the merits of our model, we use data from the literature to evaluate the performance of 10 Chinese banks, and compare the different efficiency decompositions created by different methods. Last, we apply the proposed model to the performance evaluation of sustainable product design in the automobile industry.

The Determination Method of Optimal Window Length in DEA Window Analysis

본 연구에서는 시계열데이터에 대한 효율성 분석방법으로 이용되는 DEA(Data Envelopment Analysis) Window 분석에서 최적 윈도우 길이를 결정할 수 있는 방법을 제시하였다. 최적 윈도우의 길이를 결정하기 위해서 효율성 값들에 대한 변별력 평가기준으로 Shannon의 엔트로피 기반중요도 지수를 이용하였으며, 실증분석을 통해 제안된 방법의 유용성을 입증하였다. 본 연구에서 제안된 최적 윈도우 길이 결정방법의 실증분석을 위하여 3개 예제가 적용되었다. 적용결과에 따르면 제안된 방법이 기존 방법보다 적용 가능성이 높은 것으로 분석되었다. Kruskal-Wallis 순위합 검정에 따르면 윈도우 길이에 따른 DMU들 간의 효율성 순위에는 차이가 없는 것으로 분석되었다. 따라서 최적 윈도우 길이 결정 알고리즘을 DEA Window분석에 이용할수 있다. 기존 연구에서는 명확한 변별력 평가기준 없이 비교대상 DMU의 수가 가장 많은 경우가 효율성값들에 대한 변별력이 높을 것이라는 가정을 하고 있다. 본 연구에서는 이런 문제를 해결하기 위해 엔트로피 기반 변별력 평가기준을 적용한 최적 윈도우의 길이를 결정할 수 있는 방법을 제안하였다. 본 연구에서 제안한 최적 윈도우 길이 결정방법을 적용한 결과에 따르면 전체 비교횟수가 가장 많은 경우보다 1회 비교횟수가 가장 많은 경우의 윈도우 길이가 최적 윈도우 길이라는 것이 입증되었다.This paper presents a method for determining the optimal window length in DEA window analysis which is used as an efficiency analysis method of time series data. To determine the optimal window length, an algorithm was presented to determine the optimal window length using Shannon’s Entropy-based importance weights as a criterion for discriminating against efficiency values, and empirical analysis proved the usefulness of the proposed method. In this paper, three examples are applied for the empirical analysis of the optimal window length determination method proposed in this study. According to the application results, the proposed method is more applicable than the existing methods. As a result of Kruskal-Wallis rank sum test, it is analyzed that there is no difference in efficiency ranking between DMU(Decision Making Units) according to window length, and the optimal window length selection algorithm can be used for DEA window analysis. In the previous study, it is assumed that the largest number of DMU in the comparison will have a high discriminative power on the efficiency values without a clear discriminant evaluation criterion. In this paper, we propose a method to determine optimal window length using Entropy based discriminant evaluation criterion to solve this problem. According to the result of applying the optimal window length determination method proposed in this study, it is proved that the window length in the case of the largest number of comparison times at one time is the optimal window length.

Tree aging does not affect the ranking for water use efficiency recorded from δ13C in three Populus deltoides × P. nigra genotypes

A large variability of water use efficiency (assessed from the carbon isotopic discrimination in leaves and leaf soluble sugars) has been detected among poplar genotypes. Checking whether such differences detected in young trees (1-2 years old) remain stable with tree age is a prerequisite to use this trait with confidence for breeding purposes. In this study, a synchronic approach was used to test the age-related stability of the genotypic ranking of carbon isotopic discrimination in wood (Δ13C) until tree maturity. We sampled 376 trees between 4 and 20 years from three Populus deltoides × P. nigra genotypes growing in 41 common-garden trials across France. Carbon and nitrogen percentages along with δ13C was measured in the bulk wood of the year 2009 and used to compute the Δ13C. Basal area increment between 2008 and 2009 was also measured. Results showed that Δ13C increased (i.e., water use efficiency decreased) between ages 4 to 6 and remained stable later on. Significant differences among genotypes were found but the ranking among genotypes remained stable with age during the assessed life span. Furthermore, basal area increment and Δ13C were positively correlated interannually. This large-scale survey shows that despite crossing over in the temporal trend, water use efficiency remained stable with age across 3 poplar genotypes. However, further studies with a large number of genotypes are required to confirm whether this trait can be used to maintain or even improve productivity of poplar plantations, while lowering water consumption.

Cryptocurrencies market efficiency ranking: Not so straightforward

We study the cryptocurrency market with respect to the efficient market hypothesis. Specifically, we are interested in testing whether the examined coins and tokens are efficient or not but we also compare the levels of efficiency within the cryptomarket. To do so, we utilize the Efficiency Index comprising the long-range dependence, fractal dimension and entropy components. Focusing on a set of historical currencies – Bitcoin, DASH, Litecoin, Monero, Ripple, and Stellar – as well as popular currencies and tokens of the last year (with market capitalization above $0.5 billion), we uncover some surprising results. First, the historical currencies are unanimously inefficient over the analyzed period. Second, efficiency itself and ranking as well are dependent on the denomination (the US dollar or Bitcoin). Third, most of the coins and tokens were efficient between July 2017 and June 2018. And fourth, the least efficient coins turn out to be Ethereum and Litecoin whereas DASH is the winner as the most efficient cryptocurrency.