The seventh starling

A flock of starlings wheel overhead, thousands of birds rising, falling, turning as if of one mind. Birds move in flocks; fish in schools; insects in swarms. How do they do it? Can we study them to find quantitative answers or must we simply admire them? Andrea Cavagna and Irene Giardina do both.     

抓住机遇 迎接挑战 进一步发展我国统计科学研究事业

全国统计科研工作会议迄今为止召开了五次,其中两次特别重要,即广州会议和北京平谷会议。广州会议解决了全国统计科研网络问题,各省、自治区、直辖市统计科研机构得到了强化,在全国范围内有了科研组织上的保证。北京平谷会议提出了跨世纪的统计科学研究发展纲要和加强...     

A powerful and efficient algorithm for breaking the links between aliased effects in asymmetric designs

Fractional factorial (FF) designs are no doubt the most widely used designs in experimental investigations due to their efficient use of experimental runs. One price we pay for using FF designs is, clearly, our inability to obtain estimates of some important effects (main effects or second order interactions) that are separate from estimates of other effects (usually higher order interactions). When the estimate of an effect also includes the influence of one or more other effects the effects are said to be aliased. Folding over an FF design is a method for breaking the links between aliased effects in a design. The question is, how do we define the foldover structure for asymmetric FF designs, whether regular or nonregular? How do we choose the optimal foldover plan? How do we use optimal foldover plans to construct combined designs which have better capability of estimating lower order effects? The main objective of the present paper is to provide answers to these questions. Using the new results in this paper as benchmarks, we can implement a powerful and efficient algorithm for finding optimal foldover plans which can be used to break links between aliased effects.     

Life: what is the chance that we are alone?

The Earth is full of life. If life evolved here, why not elsewhere? The Universe is a big place and our galaxy has many stars with planets. So are we alone? What is out there? And how do we know? Mark Burchell looks at the probability of life beyond our planet.     

Challenges and Opportunities for Statistics and Statistical Education: Looking Back,Looking Forward

The 175th anniversary of the ASA provides an opportunity to look back into the past and peer into the future. What led our forebears to found the association? What commonalities do we still see? What insights might we glean from their experiences and observations? I will use the anniversary as a chance to reflect on where we are now and where we are headed in terms of statistical education amidst the growth of data science. Statistics is the science of learning from data. By fostering more multivariable thinking, building data-related skills, and developing simulation-based problem solving, we can help to ensure that statisticians are fully engaged in data science and the analysis of the abundance of data now available to us.     

Uncovering the Mystery of How Users Find and Use eBooks through Guerilla Usability Testing

Abstract

This case study focuses on user research that was conducted to enhance our users’ ebook discovery experience. We took an outward-facing approach by seeking the users’ perspectives. We wanted to know: How do users find ebooks? How do they perceive multiple records for the same title? Would users find additional metadata useful, such as download availability, file format, and chapter titles? We coordinated guerilla usability testing in our library lobby, inspired by low-overhead, high-impact user experience work at other academic libraries. The resulting data gave us a much-needed new perspective of ebook usage that supplements what we already know from our day-to-day work.     

Evaluating area-wide crime-reduction measures

When we look around an imperfect world, we feel an understandable impulse to improve matters. We may therefore decide to intervene by prescribing medical treatment or by introducing crime reduction measures. But how do we know that what we do is likely to work? In medicine the standard answer is to do a trial; not surprisingly the same is true in crime reduction. But, says Paul Marchant, the lessons learned from medical trials have not been implemented in the latter field.     

Comparison and integration of subspaces from a biplot perspective

When one has information about a set of individuals on several variables, in different groups or contexts, and multivariate analysis is applied to each group the following questions arise: which groups show a similar response? how do the groups differ? how do the individuals differ in their responses in the different groups? These issues have led us to address a very interesting question in the practical context; the comparison and integration of the structures resulting from several multivariate analyses. Here we propose a method for the comparison and integration of the results arising from two Biplot analyses applied to the same variables in two different groups of individuals. By extension, we also develop the case of more than two Biplot analyses. Emphasis is placed on the underlying geometry and the interpretation of results, for which we offer indices that allow us to study the integrated structures and perform comparative analyses.     

Assessing and communicating heterogeneity of treatment effects for patient subpopulations: Keynote and panel discussion on communicating heterogeneous treatment effects across populations

How do we communicate nuanced regulatory information to different audiences, recognizing that the consumer audience is very different from the physician audience? In particular, how do we communicate the heterogeneity of treatment effects - the potential differences in treatment effects based on sex, race, and age? That is a fundamental question at the heart of this panel discussion. Each panelist addressed a specific “challenge question” during their 5-minute presentation, and the list of questions is provided. The presentations were followed by a question and answer session with members of the audience and the panelists.     

Non-parametric procedure for knockout tournaments

In a seeded knockout tournament, where teams have some preassigned strength, do we have any assurances that the best team in fact has won? Is there some insight to be gained by considering which teams beat which other teams solely examining the seeds? We pose an answer to these questions by using the difference in the seeds of the two players as the basis for a test statistic. We offer several models for the underlying probability structure to examine the null distribution and power functions and determine these for small tournaments (less than five teams). One structure each for 8 teams and 16 teams is examined, and we conjecture an asymptotic normal distribution for the test statistic.     

More Than Things

Abstract

The often invisible labor of serials, technical services, metadata, and electronic resources workers sits in the space between required and preferred, assessment and surveillance. Although libraries and information workers did not explicitly create the systems many of us live in, we are responsible for their everyday functioning. In many ways the narratives from technical services to the library are centered in objects: item counts, COUNTER stats, door counts, discovery, and other transactional data. And yet, we are stewards and maintainers, innovators and storytellers of the countless ways these objects are experienced. How can we help our colleagues understand the outreach component of this work? How do we responsibly confront power in our systems—which often miscalculates the necessity of care in favor of the shiny? What does it mean to honor expertise behind the scenes, and how might we gain agency in our systems once more?     

Digital doctoring: how to tell the real from the fake

Seeing is no longer believing. The technology that allows digital media to be manipulated and distorted is developing at breakneck speed. How do we contend with the implications? Hany Farid describes the impact of digital tampering and the development of mathematical and computational algorithms to expose digital fakes.     

Variance of the asymmetric n-player gambler’s ruin problem with ties allowed

In this article, the variance of the duration of play in the asymmetric n-player gambler’s ruin problem is considered, when the players use equal initial fortunes of d dollars, 1 ? d ? n + 1, and ties allowed in each round. Some special games are simulated and the simulation results verify the validity of the proposed formulas. It is shown that when we do not have the possibility of tie in the game, the increase in the number of players will change the ruin time from a random variable to a degenerate random variable. Finally, the three-tower problem with one of its different definitions are introduced and their expected times as well as their variances of the duration are considered.     

Altmetrics: Finding Meaningful Needles in the Data Haystack

Despite nearly 350 years of practice, we still do a fairly poor job of measuring the quality and impact of scholarly papers and the work of individual researchers. Much of our system for determining funding and career advancement revolves around one metric: the impact factor. Technology has progressed to a point where we can do better. We can now track the life of each individual paper after it has been published and better understand how it is read and how it is used. This creates a tremendous opportunity for new alternative metrics (“altmetrics”) to give us a much better sense of a paper's true impact. At the same time, we are now faced with an overwhelming quantity of information and seemingly unlimited ways to analyze a researcher's work. How do we separate out the digital needles from the haystack—the signal from the noise—and create useful tools for research assessment?     

Statistical models for short- and long-term forecasts of snow depth

Forecasting of future snow depths is useful for many applications like road safety, winter sport activities, avalanche risk assessment and hydrology. Motivated by the lack of statistical forecasts models for snow depth, in this paper we present a set of models to fill this gap. First, we present a model to do short-term forecasts when we assume that reliable weather forecasts of air temperature and precipitation are available. The covariates are included nonlinearly into the model following basic physical principles of snowfall, snow aging and melting. Due to the large set of observations with snow depth equal to zero, we use a zero-inflated gamma regression model, which is commonly used to similar applications like precipitation. We also do long-term forecasts of snow depth and much further than traditional weather forecasts for temperature and precipitation. The long-term forecasts are based on fitting models to historic time series of precipitation, temperature and snow depth. We fit the models to data from six locations in Norway with different climatic and vegetation properties. Forecasting five days into the future, the results showed that, given reliable weather forecasts of temperature and precipitation, the forecast errors in absolute value was between 3 and 7?cm for different locations in Norway. Forecasting three weeks into the future, the forecast errors were between 7 and 16?cm.     

The Minimum Wage

Do moderate increases in the minimum wage reduce employment? If not, do they nevertheless raise wages? To examine these questions, we apply techniques of time series analysis and systems estimation that are commonly used in macroeconomics and finance to five panels of data that contain between 11 and 34 low-wage industries. Our answers are “No” and “Yes,” respectively. We find that increases in the federal minimum wage between 1947 and 1997 have raised average wages in many of these industries, especially the lowest wage ones. The effect on employment, however, is mixed and typically nonsignificant, even when average wages have risen.     

Distance sampling: estimating animal density

All too often we hear in the news statements like "there are, at most, a few hundred individuals left of this endangered species" or "there is small hope for the persistence of this population given that so few are left". How do scientists count animals to make such statements? Tiago Marques explains the concepts and pitfalls of distance sampling—one of the most widely used methods for estimating animal populations.     

特有冲击、共同冲击与通货膨胀持续性

中国分类价格指数的通货膨胀持续性有何特征？如何理解分类价格指数和加总价格指数通货膨胀持续性之间的关系？我们对2001年1月至2011年12月的数据进行实证分析,结果表明分类价格指数比较明显的表现出行业间异质的通货膨胀波动性和通货膨胀持续性,而与加总价格指数相比,它的通货膨胀波动性更大而通货膨胀持续性更低。通货膨胀持续性的这些现象可以从特有冲击和共同冲击的角度加以理解。共同冲击的相对重要性存在差异解释了分类价格指数的通货膨胀持续性呈现行业间异质性;特有冲击的重要性在数据加总时被削弱,解释了分类价格指数具有比加总价格指数更低的通货膨胀持续性。     

Bayesian demography: projecting the Iraqi Kurdish population, 1977-1990

"Projecting populations that have sparse or unreliable data, such as those of many developing countries, presents a challenge to demographers. The assumptions that they make to project data-poor populations frequently fall into the realm of ?educated guesses', and the resulting projections, often regarded as forecasts, are valid only to the extent that the assumptions on which they are based reasonably represent the past or future, as the case may be. These traditional projection techniques do not incorporate a demographer's assessment of uncertainty in the assumptions. Addressing the challenges of forecasting a data-poor population, we project the Iraqi Kurdish population using a Bayesian approach. This approach incorporates a demographer's uncertainty about past and future characteristics of the population in the form of elicited prior distributions."     

Becoming familiar with multilevel modeling

Items of data vary independently of one another—or so the textbooks would have us believe. But what do you do when the data do not behave like that? Real-life populations can vary in complex ways that are dependent on each other. Harvey Goldstein introduces the mysteries of multilevel modelling.