Structure-Aware Sampling: Flexible and Accurate Summarization

In processing large quantities of data, a fundamental problem is to obtain a summary which supports approximate query answering. Random sampling yields flexible summaries which naturally support subset-sum queries with unbiased estimators and well-understood confidence bounds. Classic sample-based summaries, however, are designed for arbitrary subset queries and are oblivious to the structure in the set of keys. The particular structure, such as hierarchy, order, or product space (multi-dimensional), makes range queries much more relevant for most analysis of the data. Dedicated summarization algorithms for range-sum queries have also been extensively studied. They can outperform existing sampling schemes in terms of accuracy on range queries per summary size. Their accuracy, however, rapidly degrades when, as is often the case, the query spans multiple ranges. They are also less flexible - being targeted for range sum queries alone - and are often quite costly to build and use. In this paper we propose and evaluate variance optimal sampling schemes that are structure-aware. These summaries improve over the accuracy of existing structure-oblivious sampling schemes on range queries while retaining the benefits of sample-based summaries: flexible summaries, with high accuracy on both range queries and arbitrary subset queries

On the tradeoff between stability and fit

In computing, as in many aspects of life, changes incur cost. Many optimization problems are formulated as a one-time instance starting from scratch. However, a common case that arises is when we already have a set of prior assignments and must decide how to respond to a new set of constraints, given that each change from the current assignment comes at a price. That is, we would like to maximize the fitness or efficiency of our system, but we need to balance it with the changeout cost from the previous state. We provide a precise formulation for this tradeoff and analyze the resulting stable extensions of some fundamental problems in measurement and analytics. Our main technical contribution is a stable extension of Probability Proportional to Size (PPS) weighted random sampling, with applications to monitoring and anomaly detection problems. We also provide a general framework that applies to top-k, minimum spanning tree, and assignment. In both cases, we are able to provide exact solutions and discuss efficient incremental algorithms that can find new solutions as the input changes

The Tony Dyson Archive Project

Report of a pilot study investigating the creation of a digital archive of medieval property transactions along the City waterfron

Advantages, Challenges and Limitations of Audit Experiments with Constituents

Audit experiments examining the responsiveness of public officials have become an increasingly popular tool used by political scientists. While these studies have brought significant insight into how public officials respond to different types of constituents, particularly those from minority and disadvantaged backgrounds, audit studies have also been controversial due to their frequent use of deception. Scholars have justified the use of deception by arguing that the benefits of audit studies ultimately outweigh the costs of deceptive practices. Do all audit experiments require the use of deception? This article reviews audit study designs differing in their amount of deception. It then discusses the organizational and logistical challenges of a UK study design where all letters were solicited from MPs’ actual constituents (so-called confederates) and reflected those constituents’ genuine opinions. We call on researchers to avoid deception, unless necessary, and engage in ethical design innovation of their audit experiments, on ethics review boards to raise the level of justification of needed studies involving fake identities and misrepresentation, and on journal editors and reviewers to require researchers to justify in detail which forms of deception were unavoidable

Normalization of Function in Pediatric Dilated Cardiomyopathy Recovery or Remission?∗

Time to publication: sensitivity analyses. (DOC 62 kb

Boston Hospitality Review: Spring 2017

Table of contents: A Fragment of the Past: The System of Hotel Front Office Racks By Peter Szende and Pooja Reddy -- Changes in the Hospitality Industry: New Paradigms, Frames, and Perspectives By Mike Oshins -- Comparing apples and oranges? Examining the impacts of Airbnb on hotel performance in Boston By Tarik Dogru, Makarand Mody, and Courtney Suess -- Hospitality Healthscapes: The New Standard for Making Hospitals More Hospitable By Courtney Suess, Makarand Mody -- Hotel Brand Websites, OTA’s, Meta Search and Wholesalers: A Distribution Dilemma within the Industry By Nick Cohen -- What do guests value most in Airbnb accommodations? An application of the hedonic pricing approach By Tarik Dogru and Osman PekinA Fragment of the Past: The System of Hotel Front Office Racks By Peter Szende and Pooja Reddy -- Changes in the Hospitality Industry: New Paradigms, Frames, and Perspectives By Mike Oshins -- Comparing apples and oranges? Examining the impacts of Airbnb on hotel performance in Boston By Tarik Dogru, Makarand Mody, and Courtney Suess -- Hospitality Healthscapes: The New Standard for Making Hospitals More Hospitable By Courtney Suess, Makarand Mody -- Hotel Brand Websites, OTA’s, Meta Search and Wholesalers: A Distribution Dilemma within the Industry By Nick Cohen -- What do guests value most in Airbnb accommodations? An application of the hedonic pricing approach By Tarik Dogru and Osman Peki

Esofagectomía transhiatal por vía abierta y vía laparoscópica para el cáncer de esófago: análisis de los márgenes de resección y ganglios linfáticos

Surgical treatment of cancer of the oesophagus is associated with a high morbidity and mortality. Minimally invasive surgery has been proposed as an alternative to try to reduce these complications; however, at this time there are not many studies that evaluate the oncological validity of this method. The objective of this work is to give a preliminary audit of the results of our experience in both surgical techniques, with special emphasis on the oncopathological aspects (resection margins and lymph nodes). MATERIAL AND METHOD: Between April 2003 and February 2007, 40 patients diagnosed with distal oesophageal cancer were surgically intervened at Charing Cross Hospital, London, 24 open and 16 by laparoscopy in accordance with the surgeon responsible. Of these, 50% received neoadjuvant chemotherapy. Both groups were homogeneous for age, sex, ASA, tumour stage and tumour location. In all cases, the pathological tumour stage (TNM), the tumour distal margin, tumour proximal margin, tumour circumference and number of resected lymph nodes, were collected in a data base. RESULTS: The number of resected lymph nodes was similar in both groups; (19 for open and 18 for laparoscopy). The mean distal tumour margin for the group treated by open surgery was 4.9 cm compared to 4.3 in the group treated by laparoscopy (p = 0.578). The mean proximal tumour margin for the group treated by open surgery was 8.4 cm compared to 4.6 cm in the laparoscopy group (p = 0.004) and tumour circumference margin was positive in 11 patients (45%) belonging to the open group compared to 5 patients (33%) in the laparoscopy group (p = 0.519). CONCLUSIONS: In our experience, laparoscopic surgery for cancer of the oesophagus appears to show similar initial results to those of open surgery as regards the number of resected lymph nodes and resection margins