Cost curve evaluation of fault prediction models

Prediction of fault prone software components is one of the most researched problems in software engineering. Many statistical techniques have been proposed but there is no consensus on the methodology to select the “best model” for the specific project. In this paper, we introduce and discuss the merits of cost curve analysis of fault prediction models. Cost curves allow software quality engineers to introduce project-specific cost of module misclassification into model evaluation. Classifying a software module as fault-prone implies the application of some verification activities, thus adding to the development cost. Misclassifying a module as fault free carries the risk of system failure, also associated with cost implications. Through the analysis of sixteen projects from public repositories, we observe that software quality does not necessarily benefit from the prediction of fault prone components. The inclusion of misclassification cost in model evaluation may indicate that even the “best ” models achieve performance no better than trivial classification. Our results support a recommendation favoring the use of cost curves in practice with the hope they will become a standard tool for software quality model performance evaluation.

Homotopy Type of Complexes of Graph Homomorphisms between Cycles

In this paper we study the homotopy type of Hom(Cm,Cn), where Ck is the cyclic graph with k vertices. We enumerate connected components of Hom(Cm,Cn) and show that each such component is either homeomorphic to a point or homotopy equivalent to S1. Moreover, we prove that Hom(Cm,Ln) is either empty or is homotopy equivalent to the union of two points, where Ln is an n-string, i.e., a tree with n vertices and no branching point

Childhood Body Weight in Relation to Cause-Specific Mortality: 67 Year Follow-up of Participants in the 1947 Scottish Mental Survey

The association between childhood body weight and adult health has been little-examined, and findings are inconsistent. In a representative sample of the Scottish nation (the Scottish Mental Survey of 1947), we examined the association between body mass index measured at 11 years of age and future cause-specific mortality by age 77 years. In this cohort study, a maximum of 67 years of follow-up of 3839 study members gave rise to 1568 deaths (758 from cardiovascular disease, 610 from any malignancy). After adjustment for covariates, there was some evidence of a relation between elevated childhood body mass index and rates of mortality ascribed to all-causes (hazard ratio per 1 SD increase in body mass index; 95% confidence interval: 1.09; 1.03, 1.14), cardiovascular disease (1.09; 1.01, 1.17), all cancers combined (1.12; 1.03, 1.21), smoking-related cancers (1.13; 1.03, 1.25), and breast cancer in women (1.27; 1.04, 1.56). In conclusion, we provide further observational evidence for the need for weight control measures in youth

Attitudes to ageing and objectively-measured sedentary and walking behaviour in older people: the Lothian Birth Cohort 1936

Background:Prolonged sitting and low activity—both common in older people—are associated with increased mortality and poorer health. Whether having a more negative attitude to ageing is associated with higher levels of these behaviours is unclear.Objective:We investigated the prospective relationship between attitudes to ageing and objectively measured sedentary and walking behaviour.Methods:Participants were 271 members of the Lothian Birth Cohort 1936. At age 72 years, participants completed the Attitudes to Ageing Questionnaire which assesses attitudes on three domains—Psychosocial loss, Physical change and Psychological growth. At age 79 years, participants wore an activPAL activity monitor for seven days. The outcome measures were average daily time spent sedentary, number of sit-to-stand transitions, and step count.Results:There were no significant associations between any of the Attitude to Ageing domain scores and time spent sedentary or number of sit-to-stand transitions. In sex-adjusted analysis, having a more positive attitude to ageing as regards Physical change was associated with a slightly higher daily step count, for a SD increment in score, average daily step count was greater by 1.5% (95% CI 0.6%, 2.4%). On further adjustment for potential confounding factors these associations were no longer significant.Conclusion:We found no evidence that attitudes to ageing at age 72 were predictive of sedentary or walking behaviour seven years later. Future studies should examine whether attitudes to ageing are associated with objectively measured walking or sedentary behaviour at the same point in time. The existence of such an association could inform the development of interventions.<br/

Reparatory and Manufacturing Hard-Facing of Working Parts Made of Stainless Steels in Confectionary Industry

In this paper, for the sake of improving the reparatory hard-facing technology is especially analyzed reparatory hard-facing of tools for manufacturing compressed products in confectionary industry. Those products are being made of a mixture consisting of several powdery components, which is compressed under high pressure. In that way the connection between particles is realized, thus achieving certain hardness and strength of the confectionary product. The considered tool is made of high-alloyed stainless steel. The tool contains 30 identical working places. Besides the production process wear, on those tools, from time to time, appear mechanical damage on some of the products' shape punches, as cracks at the edges, where the products' final shapes are formed. Those damages are small, size wise, but they cause strong effect on the products' final shape. The aggravating circumstance is that the shape punch is extremely loaded in pressure, thus after the reparatory hard-facing, the additional heat treatment is necessary. Mechanical properties in the heat affected zone (HAZ) are being leveled by annealing and what also partially reduces the residual internal stresses