This paper is an attempt to understand the processes by which software ages. We define code be aged or decayed if its structure makes it unnecessarily difficult change and we measure extent of decay counting number faults in a period time. Using management data from very large, long-lived system, explore measurements history are successful predicting distribution over modules these incidences faults. In general, process measures based on more useful fault rates than product metrics code: For...

A central feature of the evolution large software systems is that change-which necessary to add new functionality, accommodate hardware, and repair faults-becomes increasingly difficult over time. We approach this phenomenon, which we term code decay, scientifically statistically. define decay propose a number measurements (code indices) on organizations produce it, serve as symptoms, risk factors, predictors decay. Using an unusually rich data set (the fifteen-plus year change history...

Abstract “Any claim coming from an observational study is most likely to be wrong.” Startling, but true. Coffee causes pancreatic cancer. Type A personality heart attacks. Trans-fat a killer. Women who eat breakfast cereal give birth more boys. All these claims come studies; yet when the studies are carefully examined, claimed links appear incorrect. What going wrong? Some have suggested that scientific method failing, nature itself playing tricks on us. But it our way of studying broken and...

Masqueraders in computer intrusion detection are people who use somebody else’s account. We investigate a number of statistical approaches for detecting masqueraders. To evaluate them, we collected UNIX command data from 50 users and then contaminated the with The experiment was blinded. show results six methods, including two science community.

The goal of this research was to study the relationship between cracking and concrete permeability support accounting for resistance other factors besides strength, as criteria be considered in mix design achieve a durable concrete. effect material composition [normal-strength (NSC) high-strength (HSC) with two different designs] crack width (ranging from 50 400 μm) on water chloride were examined. Cracks designed widths induced specimens using feedback-controlled splitting tensile test....

Techniques are developed for nonparametric analysis of data under a Cox-regression-like model permitting time-dependent covariate effects determined by regression function $\beta_0(t)$. Estimators resulting from maximization an appropriate penalized partial likelihood shown to exist and computational approach is outlined. Weak uniform consistency (with rate convergence) pointwise asymptotic normality the estimators established regularity conditions. A consistent estimator common baseline...

When releasing data to the public, statistical agencies and survey organizations typically alter values in order protect confidentiality of respondents' identities attribute values. To select among wide variety alteration methods, require tools for evaluating utility proposed releases. Such measures can be combined with disclosure risk gauge risk-utility tradeoffs competing methods. This article presents focused on differences inferences obtained from altered corresponding original data....

3. Point Processes and Their Statistical Inference, 2nd edn. By A. F. Karr. ISBN 0 8247 8532 0. Dekker, New York, 1991. 490 pp. $126.50.

When releasing microdata to the public, data disseminators typically alter original protect confidentiality of database subjects' identities and sensitive attributes. However, such alteration negatively impacts utility (quality) released data. In this paper, we present quantitative measures for masked microdata, with aim improving disseminators' evaluations competing masking strategies. The measures, which are global in that they reflect similarities between entire distributions data,...

Reluctance of data owners to share their possibly confidential or proprietary with others who own related databases is a serious impediment conducting mutually beneficial mining analysis. We address the case vertically partitioned -- multiple owners/agencies each possess few attributes every record. focus on agencies wanting conduct linear regression analysis complete records without disclosing values attributes. This paper describes an algorithm that enables such compute exact coefficients...

This article presents several methods for performing linear regression on the union of distributed databases that preserve, to varying degrees, confidentiality those databases. Such can be used by federal or state statistical agencies share information from their individual databases, make such available others. Secure data integration, which provides lowest level protection, actually integrates but in a manner no database owner determine origin any records other than its own. Regression,...

A key problem in software engineering is changing the code. We present a sequence of visualizations and visual metaphors designed to help engineers understand manage change process. The principal are matrix views, cityscapes, bar pie charts, data sheets networks. Linked by selection mechanisms, multiple views combined form perspectives that both enable discovery high-level structure allow effective access details those data. Use illustrated two important contexts: understanding exploration...

This research explores the relationship between permeability and crack width in cracked, steel fiber-reinforced concrete. In addition, it inspects influence of fiber reinforcement on concrete permeability. The feedback-controlled splitting tension test (also known as Brazilian test) is used to induce cracks up 500 μm (0.02 in.) specimens without reinforcement, with volumes both 0.5 1%. relax after induced cracking. fibers decrease relaxed larger than 100 μm.