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Feature-Oriented Defect Prediction: Scenarios, Metrics, and Classifiers [article]

Mukelabai Mukelabai, Stefan Strüder, Daniel Strüber, Thorsten Berger
2021 arXiv   pre-print
Several software defect prediction techniques have been developed over the past decades. These techniques predict defects at the granularity of typical software assets, such as components and files. In this paper, we investigate feature-oriented defect prediction: predicting defects at the granularity of features -- domain-entities that represent software functionality and often cross-cut software assets. Feature-oriented defect prediction can be beneficial since: (i) some features might be
more » ... error-prone than others, (ii) characteristics of defective features might be useful to predict other error-prone features, and (iii) feature-specific code might be prone to faults arising from feature interactions. We explore the feasibility and solution space for feature-oriented defect prediction. Our study relies on 12 software projects from which we analyzed 13,685 bug-introducing and corrective commits, and systematically generated 62,868 training and test datasets to evaluate classifiers, metrics, and scenarios. The datasets were generated based on the 13,685 commits, 81 releases, and 24, 532 permutations of our 12 projects depending on the scenario addressed. We covered scenarios such as just-in-time (JIT) and cross-project defect prediction. Our results confirm the feasibility of feature-oriented defect prediction. We found the best performance (i.e., precision and robustness) when using the Random Forest classifier, with process and structure metrics. Surprisingly, single-project JIT and release-level predictions had median AUC-ROC values greater than 95% and 90% respectively, contrary to studies that assert poor performance due to insufficient training data. We also found that a model trained on release-level data from one of the twelve projects could predict defect-proneness of features in the other eleven projects with median AUC-ROC of 82%, without retraining.
arXiv:2104.06161v1 fatcat:w6gsqtxqlnhg5asqbbanyebmqu

Seamless Variability Management With the Virtual Platform [article]

Wardah Mahmood, Daniel Strüber, Thorsten Berger, Ralf Lämmel, Mukelabai Mukelabai
2021 arXiv   pre-print
Customization is a general trend in software engineering, demanding systems that support variable stakeholder requirements. Two opposing strategies are commonly used to create variants: software clone & own and software configuration with an integrated platform. Organizations often start with the former, which is cheap, agile, and supports quick innovation, but does not scale. The latter scales by establishing an integrated platform that shares software assets between variants, but requires
more » ... up-front investments or risky migration processes. So, could we have a method that allows an easy transition or even combine the benefits of both strategies? We propose a method and tool that supports a truly incremental development of variant-rich systems, exploiting a spectrum between both opposing strategies. We design, formalize, and prototype the variability-management framework virtual platform. It bridges clone & own and platform-oriented development. Relying on programming-language-independent conceptual structures representing software assets, it offers operators for engineering and evolving a system, comprising: traditional, asset-oriented operators and novel, feature-oriented operators for incrementally adopting concepts of an integrated platform. The operators record meta-data that is exploited by other operators to support the transition. Among others, they eliminate expensive feature-location effort or the need to trace clones. Our evaluation simulates the evolution of a real-world, clone-based system, measuring its costs and benefits.
arXiv:2103.00437v2 fatcat:suopwoufubc5xjrjzyq6gbeqze

A Study of Feature Scattering in the Linux Kernel

Leonardo Passos, Rodrigo Queiroz, Mukelabai Mukelabai, Thorsten Berger, Sven Apel, Krzysztof Czarnecki, Jesus Alejandro Padilla
2020 Software Engineering  
Feature code is often scattered across a software system. Scattering is not necessarily bad if used with care, as witnessed by systems with highly scattered features that evolved successfully. Feature scattering, often realized with a pre-processor, circumvents limitations of programming languages and software architectures. Unfortunately, little is known about the principles governing scattering in large and long-living software systems. We present a longitudinal study of feature scattering in
more » ... the Linux kernel, complemented by a survey with 74, and interviews with nine Linux kernel developers. We analyzed almost eight years of the kernel's history, focusing on its largest subsystem: device drivers. We learned that the ratio of scattered features remained nearly constant and that most features were introduced without scattering. Yet, scattering easily crosses subsystem boundaries, and highly scattered outliers exist. Scattering often addresses a performance-maintenance tradeoff (alleviating complicated APIs), hardware design limitations, and avoids code duplication. While developers do not consciously enforce scattering limits, they actually improve the system design and refactor code, thereby mitigating pre-processor idiosyncrasies or reducing its use.
doi:10.18420/se2020_23 dblp:conf/se/PassosQMBACP20 fatcat:myw2knf7d5bk3ngomwjjpphyg4

Tackling combinatorial explosion: a study of industrial needs and practices for analyzing highly configurable systems

Mukelabai Mukelabai, Damir Nešić, Salome Maro, Thorsten Berger, Jan-Philipp Steghöfer
2019 Software Engineering  
Hundreds of dedicated analysis techniques for highly configurable systems have been conceived, many of them able to analyze properties for all possible system configurations. Unfortunately, it is largely unknown whether these techniques are adopted in practice, whether they address actual needs, or which strategies practitioners apply. We present a study [MNM+18] of analysis practices and needs in industry based on surveys and interviews. We confirm that properties considered in the literature
more » ... e.g., reliability) are relevant and that consistency between variability models and artifacts is critical, but that the majority of analyses for specifications of configuration options (a.k.a., variability model analysis) is not perceived as needed. We identified pragmatic analysis strategies, including practices to avoid the need for analysis. We discuss analyses that are missing and synthesize our insights into suggestions for future research.
doi:10.18420/se2019-21 dblp:conf/se/MukelabaiNMBS19 fatcat:lsxnyyfvjnatxpn3ucwf342r3i

Towards a Better Understanding of Software Features and Their Characteristics

Jacob Krüger, Wanzi Gu, Hui Shen, Mukelabai Mukelabai, Regina Hebig, Thorsten Berger
2018 Proceedings of the 12th International Workshop on Variability Modelling of Software-Intensive Systems - VAMOS 2018  
The notion of features is commonly used to describe, structure, and communicate the functionalities of a system. Unfortunately, features and their locations in software artifacts are rarely made explicit and often need to be recovered by developers. To this end, researchers have conceived automated feature-location techniques. However, their accuracy is generally low, and they mostly rely on few information sources, disregarding the richness of modern projects. To improve such techniques, we
more » ... d to improve the empirical understanding of features and their characteristics, including the information sources that support feature location. Even though, the product-line community has extensively studied features, the focus was primarily on variable features in preprocessor-based systems, largely side-stepping mandatory features, which are hard to identify. We present an exploratory case study on identifying and locating features. We study what information sources reveal features and to what extent, compare the characteristics of mandatory and optional features, and formulate hypotheses about our observations. Among others, we find that locating features in code requires substantial domain knowledge for half of the mandatory features (e.g., to connect keywords) and that mandatory and optional features in fact differ. For instance, mandatory features are less scattered. Other researchers can use our manually created data set of features locations for future research, guided by our formulated hypotheses. CCS CONCEPTS • Software and its engineering → Software product lines; Software reverse engineering; KEYWORDS Feature location, preprocessor, Marlin, case study ACM Reference Format:
doi:10.1145/3168365.3168371 dblp:conf/vamos/KrugerGSMHB18 fatcat:4i2d7pun4bbx3jakns6tre6laa

Observations on Zambia's Crop Monitoring and Early Warning Systems

Gelson Tembo, Bernadette Chimai, Nathan Tembo, Mukelabai Ndiyoi
2014 Journal of Agricultural Science  
A good early warning system is one that provides timely planning information to a diverse set of stakeholders. While policy makers need very concise messages for quick decisions, aid and development agencies need very specific and detailed information which can help them in programming at grass-roots level. This paper reviews Zambia's crop monitoring and early warning systems and suggests practical ways to improve its efficiency and effectiveness, taking advantage of existing and potential
more » ... gistic and institutional opportunities. In much of southern Africa, existing early warning information systems often are inadequate and not timely enough. The observed levels of vulnerability to weather-related shocks are also very high and tend to be exacerbated by a number of underlying factors, including poor access to basic inputs such as seed and fertilizer; loss of livestock, draught power and other production inputs; the devastating effects of HIV/AIDS on the households; and inadequate extension services. Food shortages are frequent and, quite often, very serious. The need for a quicker and cost-effective season and crop monitoring system is fully recognized by the governments and their cooperating partners. Donor-supported efforts in early warning systems of ministries of agriculture, such as Zambia's FAO-supported Crop Monitoring Survey Project (CMSP), have helped fill some of the information gaps. However, it is recognized that such arrangements are of limited value unless they are part of and facilitate strengthening of existing institutions. These and other such initiatives present a unique opportunity to draw lessons for building national and regional capacities to develop effective early warning systems. This paper summarizes the experiences associated with past and existing early warning initiatives with emphasis on lessons for improvement. In the rest of the paper, we first review conceptually the need for an effective early warning system (Section 2), followed by a summary of the existing crop monitoring systems in Zambia (Section 3) and suggestions to improve existing systems (Section 4). Section 5 presents some concluding remarks and recommendations. The Need for an Effective Early Warning System An effective early warning system needs to have four inter-related elements (Figure 1 ): i) Continuous monitoring of the precursors (or indicators), which is critical for understanding the risks from both the hazards and people's vulnerabilities; ii) forecasting of a probable event, and, if the probability is high enough; iii) appropriate measures
doi:10.5539/jas.v6n3p99 fatcat:mfnr67lyknfg3jbgmg2gxk2di4

Infrastructure Watch Culture: Zambia's Infrastructure Report Card

Mundia Muya, Chisanga Kaluba, Ian Nzali Banda, Suzanne Rattray, Christopher Mubemba, Garry Mukelabai
2017 Civil engineering and architecture  
Every country needs a well-maintained public infrastructure system to deliver essential services to its citizens and propel economic growth. The Engineering Institution of Zambia carried out a comprehensive study on the state of public infrastructure in Zambia and produced the country's first ever 'report card'. A team of experts assessed the state of infrastructure based on four criteria: condition; capacity; operations; and security. The purpose of the report card was to sensitize the
more » ... nt and the general public about the condition and performance of engineering infrastructure in the country. The report covered seven categories comprising: roads and bridges; water supply, sanitation and solid waste; electricity; information and communication technology; and airports and railway infrastructure. These were graded on a scale A to F where Grade A was awarded to infrastructure that was adequate for present and future use and F to that which was totally inadequate. Overall, the infrastructure system was found to be inadequate to meet present and future needs in a number of aspects.
doi:10.13189/cea.2017.050102 fatcat:raoixrtvl5aizjhrlpitfgwnhq

Time‐series validation of MODIS land biophysical products in a Kalahari woodland, Africa

K. F. Huemmrich, J. L. Privette, M. Mukelabai, R. B. Myneni, Y. Knyazikhin
2005 International Journal of Remote Sensing  
Monthly measurements of leaf area index (LAI) and the fraction of absorbed photosynthetically active radiation (f APAR ) taken at approximately monthly intervals were collected along three 750 m transects in a Kalahari woodland near Mongu in western Zambia. These data were compared with MODIS NDVI (MOD13, Collection 3) and MODIS LAI and f APAR products (MOD15, Collection 3) over a 2 year period (2000)(2001)(2002). MODIS and ground-measured LAI values corresponded well, while there was a
more » ... ant bias between MODIS and ground-measured f APAR even though both MODIS variables are produced from the same algorithm. Solar zenith angle effects, differences between intercepted and absorbed photosynthetically active radiation, and differences in measurement of f APAR (photon counts versus energy) were examined and rejected as explanations for the discrepancies between MODIS and groundmeasured f APAR . Canopy reflectance model simulations produced different values of f APAR with the same LAI when canopy cover was varied, indicating that errors in the estimation of canopy cover in the MODIS algorithm due to the land cover classification used are a possible cause of the f APAR discrepancy. This is one of the first studies of MODIS land product performance in a time-series context. Despite a bias in f APAR , our results demonstrate that the woodland canopy phonology is captured in the MODIS product.
doi:10.1080/01431160500113393 fatcat:e6gkpoyawba4bi6ekycm6cjcqu

The charcoal trap: Miombo forests and the energy needs of people

Werner L Kutsch, Lutz Merbold, Waldemar Ziegler, Mukufute M Mukelabai, Maurice Muchinda, Olaf Kolle, Robert J Scholes
2011 Carbon Balance and Management  
doi:10.1186/1750-0680-6-5 pmid:21854587 pmcid:PMC3189094 fatcat:6lema5eykfaqzh25tvsbctkw5i

Vegetation structure characteristics and relationships of Kalahari woodlands and savannas

J.L. Privette, Y. Tian, G. Roberts, R.J. Scholes, Y. Wang, K.K. Caylor, P. Frost, M. Mukelabai
2004 Global Change Biology  
The Kalahari Transect is one of several International Geosphere-Biosphere Programme (IGBP) transects designed to address global change questions at the regional scale, in particular by exploiting natural parameter gradients (Koch et al., 1995) . In March 2000, we collected near-synoptic vegetation structural data at five sites spanning the Kalahari's large precipitation gradient (about 300-1000 mm yr À1 ) from southern Botswana ( $ 241S) to Zambia ( $ 151S). All sites were within the expansive
more » ... alahari sandsheet. Common parameters, including plant area index (PAI), leaf area index (LAI) and canopy cover (CC), were measured or derived using several indirect instruments and at multiple spatial scales. Results show that CC and PAI increase with increasing mean annual precipitation. Canopy clumping, defined by the deviation of the gap size distribution from that of randomly distributed foliage, was fairly constant along the gradient. We provide empirical relationships relating these parameters to each other and to precipitation. These results, combined with those in companion Kalahari Transect studies, provide a unique and coherent test bed for ecological modeling. The data may be used to parameterize process models, as well as test internally predicted parameters and their variability in response to well-characterized climatological differences.
doi:10.1111/j.1365-2486.2004.00740.x fatcat:kqxzkfwgtnagjovbu3ogadppk4

Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia

L. Merbold, W. Ziegler, M. M. Mukelabai, W. L. Kutsch
2011 Biogeosciences  
Carbon dioxide efflux from the soil surface was measured over a period of several weeks within a heterogeneous Brachystegia spp. dominated miombo woodland in Western Zambia. The objectives were to examine spatial and temporal variation of soil respiration along a disturbance gradient from a protected forest reserve to a 5 cut, burned, and grazed area outside, and to relate the flux to various abiotic and biotic drivers. The highest daily mean fluxes (around 12 µmol m −2 s −1 ) were measured in
more » ... he protected forest in the wet season and lowest daily mean fluxes (around 1 µmol m −2 s −1 ) in the most disturbed area during the dry season. Diurnal variation of soil respiration was closely correlated with soil temperature. The combination of soil 10 BGD 7, 5757-5800, 2010 tion, and to compare "top-down" (eddy covariance) and "bottom-up" (chambers) methods of estimating ecosystem respiration. This objective had four sub-objectives: to investigate (i) the temporal variation of soil respiration for periods of hours to years, (ii) the spatial heterogeneity of soil respiration at scales of meters to hundreds of meters, and (iii) the abiotic and biotic factors that drive this heterogeneity. In particular (iv), we 5 BGD 7, 5757-5800, 2010 Abstract In the surrounding disturbed areas, the dominant species are shrubs such as Diospy-5761 BGD 7, 5757-5800, 2010 ros batoeana (20.8 %) and Baphia obovata (10.4%) and large amounts of C 4 grasses that invade shortly after clear-cutting. The soils are deep, nutrient poor Arenosols (FAO soil group). Kataba falls within the vast basin of "Kalahari sands". For more detailed information we refer to Scholes et al. (2004) and Scanlon and Albertson (2004). Abstract BGD 7, 5757-5800, 2010 Abstract BGD 7, 5757-5800, 2010 Abstract the autotrophic component to RSWC seems likely but is unrealistic from the biological 5765 BGD 7, 5757-5800, 2010 Abstract BGD 7, 5757-5800, 2010 Abstract BGD 7, 5757-5800, 2010 Abstract BGD 7, 5757-5800, 2010 Abstract BGD 7, 5757-5800, 2010 Abstract 20 to 25% for the different plots (grey dots in Fig. 9 ). On the other hand the night-time based model including a response to soil water content and temperature clearly overestimated fluxes in the wet seasons (black dots). Generally, each model had its strengths, either for the disturbed or undisturbed plots in the dry and the wet season (not shown). Similarly each top-down approach had 25 its weaknesses. The best fit was given by the method using night-time data and soil temperature as a predictor of R eco , only (white dots). Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010 Abstract 7, 5757-5800, 2010
doi:10.5194/bg-8-147-2011 fatcat:hdq72ea3lnbbdnj4byzwdsaf4e

Community-level Impacts of AIDS-Related Mortality: Panel Survey Evidence from Zambia*

Thomas S. Jayne, Antony Chapoto, Elizabeth Byron, Mukelabai Ndiyoi, Petan Hamazakaza, Suneetha Kadiyala, Stuart Gillespie
2006 Review of Agricultural Economics  
African rural communities display great heterogeneity in their farming systems, population densities, and local institutions which would suggest that the impacts of HIV/AIDS may differ across communities. Using nationally-representative longitudinal data on 5,420 households in 396 communities in rural Zambia, we find that communities having similar HIV prevalence and adult mortality rates show significant variations in indicators of economic and social welfare over time. Variation in
more » ... evel resilience to HIV/AIDS provides an opportunity to identify exogenous factors influencing community resilience. In general, we find that the effects of AIDS-related mortality on rural livelihoods are complex in that they depend significantly on initial community conditions such as the level of mean education, wealth, farm size, population density, connectedness with markets and infrastructure, and dependency ratios. Our results find relatively small independent effects of prime-age mortality on community crop output, mean income, and income per capita. However, the estimated effects become large in some communities displaying particular initial community conditions. These results provide important clues as to the factors influencing communities' resilience, or ability to withstand the impacts of increased AIDS-related mortality. A growing literature has focused on understanding the effects of the HIV/AIDS pandemic on rural livelihoods and the agricultural sectors in Africa (Ainsworth, Fransen, and Over; Barnett and Whiteside; Gillespie and Kadiyala; Mather et al.). In some parts of southern Africa, HIV prevalence rates are as high as 30 percent among individuals between 15-45 years. Several nationwide household panel surveys from relatively hard-hit countries (Kenya, Tanzania, and Zambia) indicate that, over a 3-year survey interval, roughly 6-10% of rural households suffer one or more disease-related deaths of a prime-aged individual (Yamano and Jayne; Beegle; Chapoto and Jayne), and there is overwhelming evidence that most of the mortality in these age ranges is related to AIDS (Ngom and Clark).
doi:10.1111/j.1467-9353.2006.00310.x fatcat:j47wlz6ho5hfleekkryxixy6ue

Early spatial and temporal validation of MODIS LAI product in the Southern Africa Kalahari

J.L Privette, R.B Myneni, Y Knyazikhin, M Mukelabai, G Roberts, Y Tian, Y Wang, S.G Leblanc
2002 Remote Sensing of Environment  
Mukelabai, unpublished data). Thus, we expect our results to change little upon MODIS reprocessing. Other limitations to our results are discussed below.  ... 
doi:10.1016/s0034-4257(02)00075-5 fatcat:c2yxsbvofnhjbjco3auzeua2v4

Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia

L. Merbold, W. Ziegler, M. M. Mukelabai, W. L. Kutsch
2010 Biogeosciences Discussions  
Carbon dioxide efflux from the soil surface was measured over a period of several weeks within a heterogeneous Brachystegia spp. dominated miombo woodland in Western Zambia. The objectives were to examine spatial and temporal variation of soil respiration along a disturbance gradient from a protected forest reserve to a cut, burned, and grazed area outside, and to relate the flux to various abiotic and biotic drivers. The highest daily mean fluxes (around 12 µmol CO 2 m −2 s −1 ) were measured
more » ... n the protected forest in the wet season and lowest daily mean fluxes (around 1 µmol CO 2 m −2 s −1 ) in the most disturbed area during the dry season. Diurnal variation of soil respiration was closely correlated with soil temperature. The combination of soil water content and soil temperature was found to be the main driving factor at seasonal time scale. There was a 75% decrease in soil CO 2 efflux during the dry season and a 20% difference in peak soil respiratory flux measured in 2008 and 2009. Spatial variation of CO 2 efflux was positively related to total soil carbon content in the undisturbed area but not at the disturbed site. Coefficients of variation of efflux rates between plots decreased towards the core zone of the protected forest reserve. Normalized soil respiration values did not vary significantly along the disturbance gradient. Spatial variation of respiration did not show a clear distinction between the disturbed and undisturbed sites and could not be explained by variables such as leaf area index. In contrast, within plot variability of soil respiration was explained by soil organic carbon content. Correspondence to: L. Merbold ( Three different approaches to calculate total ecosystem respiration (R eco ) from eddy covariance measurements were compared to two bottom-up estimates of R eco obtained from chambers measurements of soil-and leaf respiration which differed in the consideration of spatial heterogeneity. The consideration of spatial variability resulted only in small changes of R eco when compared to simple averaging. Total ecosystem respiration at the plot scale, obtained by eddy covariance differed by up to 25% in relation to values calculated from the soil-and leaf chamber efflux measurements but without showing a clear trend.
doi:10.5194/bgd-7-5757-2010 fatcat:wuzl26luebhpffrv3mveo255rq

The Impact of Upcoming Treatments in Huntington's Disease: Resource Capacity Limitations and Access to Care Implications

Mark Guttman, Marco Pedrazzoli, Marina Ponomareva, Marsha Pelletier, Louisa Townson, Kopano Mukelabai, Aaron Levine, Anna-Lena Nordström, Ralf Reilmann, Jean-Marc Burgunder
2021 Journal of Huntington's Disease  
CONFLICT OF INTEREST Louisa Townson, Kopano Mukelabai, Aaron Levine and Anna-Lena Nordström are employees of F. Hoffmann-La Roche Ltd.  ... 
doi:10.3233/jhd-200462 pmid:33843690 fatcat:smfcajrrnncdbfzxwn742ndrna
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