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113 results on '"Guttag J"'

2. Comparing Precision Machine Learning With Consumer, Quality, and Volume Metrics for Ranking Orthopedic Surgery Hospitals: Retrospective Study

Author

Goyal, D, Guttag, J, Syed, Z, Mehta, R, Elahi, Z, Saeed, M, Goyal, D, Guttag, J, Syed, Z, Mehta, R, Elahi, Z, and Saeed, M

Abstract

BACKGROUND: Patients' choices of providers when undergoing elective surgeries significantly impact both perioperative outcomes and costs. There exist a variety of approaches that are available to patients for evaluating between different hospital choices. OBJECTIVE: This paper aims to compare differences in outcomes and costs between hospitals ranked using popular internet-based consumer ratings, quality stars, reputation rankings, average volumes, average outcomes, and precision machine learning-based rankings for hospital settings performing hip replacements in a large metropolitan area. METHODS: Retrospective data from 4192 hip replacement surgeries among Medicare beneficiaries in 2018 in a the Chicago metropolitan area were analyzed for variations in outcomes (90-day postprocedure hospitalizations and emergency department visits) and costs (90-day total cost of care) between hospitals ranked through multiple approaches: internet-based consumer ratings, quality stars, reputation rankings, average yearly surgical volume, average outcome rates, and machine learning-based rankings. The average rates of outcomes and costs were compared between the patients who underwent surgery at a hospital using each ranking approach in unadjusted and propensity-based adjusted comparisons. RESULTS: Only a minority of patients (1159/4192, 27.6% to 2078/4192, 49.6%) were found to be matched to higher-ranked hospitals for each of the different approaches. Of the approaches considered, hip replacements at hospitals that were more highly ranked by consumer ratings, quality stars, and machine learning were all consistently associated with improvements in outcomes and costs in both adjusted and unadjusted analyses. The improvement was greatest across all metrics and analyses for machine learning-based rankings. CONCLUSIONS: There may be a substantive opportunity to increase the number of patients matched to appropriate hospitals across a broad variety of ranking approaches. Elective hip r

Published
2021

3. Estimation of Bounds on Potential Outcomes For Decision Making

Author

Makar, M., Fredrik Johansson, Guttag, J., and Sontag, D.

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Statistics - Machine Learning, Machine Learning (stat.ML), Machine Learning (cs.LG)
Abstract

Estimation of individual treatment effects is commonly used as the basis for contextual decision making in fields such as healthcare, education, and economics. However, it is often sufficient for the decision maker to have estimates of upper and lower bounds on the potential outcomes of decision alternatives to assess risks and benefits. We show that, in such cases, we can improve sample efficiency by estimating simple functions that bound these outcomes instead of estimating their conditional expectations, which may be complex and hard to estimate. Our analysis highlights a trade-off between the complexity of the learning task and the confidence with which the learned bounds hold. Guided by these findings, we develop an algorithm for learning upper and lower bounds on potential outcomes which optimize an objective function defined by the decision maker, subject to the probability that bounds are violated being small. Using a clinical dataset and a well-known causality benchmark, we demonstrate that our algorithm outperforms baselines, providing tighter, more reliable bounds.

Published
2019

4. Proof rules for the programming language Euclid

Author

London, R. L., Guttag, J. V., Horning, J. J., Lampson, B. W., Mitchell, J. G., Popek, G. J., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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11. Memory assignment for multiprocessor caches through grey coloring

Author

Agarwal, A., Guttag, J. V., Hadjicostis, Christoforos N., Papaefthymiou, M. C., Maritsas D., Theodoridis S., Halatsis C., Philokyprou G., and Hadjicostis, Christoforos N. [0000-0002-1706-708X]

Subjects
Cache utilization, Hardware_MEMORYSTRUCTURES, Parallel architectures, Multiprocessing systems, Multiprocessor cache, Cache memory, Buffer storage, Finding solutions, Cache miss, Memory architecture, Cache performance
Abstract

The achieved performance of multiprocessors is heavily dependent on the performance of their caches. Cache performance is severely degraded when data tiles used by a program conflict in the caches. This paper explores techniques for improving multiprocessor performance by improving cache utilization. Specifically, we investigate the problem of statically assigning data tiles to memory in a way that minimizes the impact of collisions in multiprocessor caches. We define the problem precisely and present an efficient procedure for finding solutions to it. The procedure incorporates a new technique, grey coloring, that reduces the maximum number of conflicts in any cache in the system by distributing cache misses evenly among processors. © Springer-Verlag Berlin Heidelberg 1994. 817 LNCS Journal Article 351 362

Published
1994

23. Virtual radios

Author

Bose, V., primary, Ismert, M., additional, Welborn, M., additional, and Guttag, J., additional

Published
1999
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27. Prototyping

Author

Balzer, R, primary, Belz, F, additional, Dewar, R, additional, Fisher, D, additional, Gabriel, R, additional, Guttag, J, additional, Hudak, P, additional, and Wand, M, additional

Published
1990
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28. The algebraic specification of abstract data types.

Author

Guttag, J. and Horning, J.

Abstract

There have been many recent proposals for embedding abstract data types in programming languages. In order to reason about programs using abstract data types, it is desirable to specify their properties at an abstract level, independent of any particular implementation. This paper presents an algebraic technique for such specifications, develops some of the formal properties of the technique, and shows that these provide useful guidelines for the construction of adequate specifications. [ABSTRACT FROM AUTHOR]

Published
1978
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29. Preliminary Report on the Larch Shared Language.

Author

MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR COMPUTER SCIENCE, Guttag,J V, Horning,J J, MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR COMPUTER SCIENCE, Guttag,J V, and Horning,J J

Abstract

Each member of the Larch family of formal specification languages has a component derived from a programming language and another component common to all programming languages. The authors call the former interface languages, and the latter the Larch Shared Language. This report presents version 1.0 of the Larch Shared Language. It begins with a brief introduction to the Larch Project and the Larch family of languages. The next chapter presents most of the features of the Larch Shared Language and briefly discusses how we expect these features to be used. It should be read before reading either of the remaining two chapters, which are a self-contained reference manual and a set of examples. (Author)

Published
1983

39. Clustering and Symbolic Analysis of Cardiovascular Signals: Discovery and Visualization of Medically Relevant Patterns in Long-Term Data Using Limited Prior Knowledge

Author

Syed Zeeshan, Guttag John, and Stultz Collin

Subjects
Telecommunication, TK5101-6720, Electronics, TK7800-8360
Abstract

This paper describes novel fully automated techniques for analyzing large amounts of cardiovascular data. In contrast to traditional medical expert systems our techniques incorporate no a priori knowledge about disease states. This facilitates the discovery of unexpected events. We start by transforming continuous waveform signals into symbolic strings derived directly from the data. Morphological features are used to partition heart beats into clusters by maximizing the dynamic time-warped sequence-aligned separation of clusters. Each cluster is assigned a symbol, and the original signal is replaced by the corresponding sequence of symbols. The symbolization process allows us to shift from the analysis of raw signals to the analysis of sequences of symbols. This discrete representation reduces the amount of data by several orders of magnitude, making the search space for discovering interesting activity more manageable. We describe techniques that operate in this symbolic domain to discover rhythms, transient patterns, abnormal changes in entropy, and clinically significant relationships among multiple streams of physiological data. We tested our techniques on cardiologist-annotated ECG data from forty-eight patients. Our process for labeling heart beats produced results that were consistent with the cardiologist supplied labels 98.6 of the time, and often provided relevant finer-grained distinctions. Our higher level analysis techniques proved effective at identifying clinically relevant activity not only from symbolized ECG streams, but also from multimodal data obtained by symbolizing ECG and other physiological data streams. Using no prior knowledge, our analysis techniques uncovered examples of ventricular bigeminy and trigeminy, ectopic atrial rhythms with aberrant ventricular conduction, paroxysmal atrial tachyarrhythmias, atrial fibrillation, and pulsus paradoxus.

Published
2007

42. Program inversion

Author

Dijkstra, Edsger W., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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43. The Schorr-Waite graph marking algorithm

Author

Gries, David, Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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44. On the interplay between mathematics and programming

Author

Dijkstra, E. W., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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45. Some theoretical aspects of program construction

Author

Pair, Claude, Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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46. Towards a wide spectrum language to support program specification and program development

Author

Bauer, F. L., Broy, M., Gnatz, R., Hesse, W., Krieg-Brücknert, B., Partsch, H., Pepper, P., Wössner, H., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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47. Finding the correctness proof of a concurrent program

Author

Dijkstra, Edsger W., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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48. Programming methodology and language implications

Author

Griffiths, Michael, Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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49. Notes on type abstraction

Author

Guttag, John, Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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50. Examples for change of types and object structures

Author

Partsch, H., Broy, M., Goos, G., editor, Hartmanis, J., editor, Brinch Hansen, P., editor, Gries, D., editor, Moler, C., editor, Seegmüller, G., editor, Stoer, J., editor, Wirth, N., editor, Bauer, Friedrich L., editor, Broy, Manfred, editor, Dijkstra, E. W., editor, Gerhart, S. L., editor, Griffiths, M., editor, Guttag, J. V., editor, Horning, J. J., editor, Owicki, S. S., editor, Pair, C., editor, Partsch, H., editor, Pepper, P., editor, Wirsing, M., editor, and Wössner, H., editor

Published
1979
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