That t linear model is faults modules that c 9 is

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Unformatted text preview: but recent andBoth generalized linear the of the to fault havethese yet done this. ofchange a module has analysis employson variant of the sets but requirin based a larger data we potential and the illuminate times as the primary are less likely to have predictive CDI EF not indices number lines agentAn alternative (and less powerful) model, using the CDI ªsum of touched file sizesº changes given creating though faults doeqi…m arise not n are been changed is faults. (EvenX a tbetter predictorc than its size of †the with the effort for individual term in (6) omit sa 1f e> m absence ; …S† p€qvw this is not  spontaneously,…m; † ˆ P a tautology: The g  of other results are suggestivein [25].) of (5) faults it will suffer asthe a generalized 0 is the high values, is but, because of the small sam es of number ofand the same datainPÁ future. That Tˆ linear model, is faults. Modules that c (9), is highly informative.) terms such as size and complexity not definitive. that nes g at a primary (and direct) evidence X changes induce faults: frequentExtreme variability of theafeature-le changes are 10 The indices, depictchanges deltas c upmsize would…mthe In (4), : The taking logarithms of from set of 54 > where FP0the…entire:017ofoftemporal effects.:64t andbe Áˆ GLM m† ˆ set is past differing thef same to time AGE †eqi is † model was fit using dataall variables. (Th g … line the Where of changes are ªdampedº1andeattenuate over time, As 10 in Section 2.1, effects m notedtion, log‰1 haveavoids negative num high c indistinguishable from one another where , none could P areore likely to ‡ ÁŠ, features are the units of discussed in Section 4.2.4 and and, hence, , I , and stand while in (5), faults are less likely in older code (provided b is functionality (e.g., call waiting) by which the sy ted be posited to have any specific effect. fhave and is aults nged estimated using statistical analysis. This model implies that code having many lines thatextended modelare too aggregated for most pu and The modelthese indices illuminate that some modules (9) does provide Both ofchanges are long ratherevidence change as the primary of 10. Here, survived for a deltas time than MRs. (person hours) nes are more decayed than others. Inis likely to be relatively free principle, this issue could However, effort…dataEFF…c†† ˆ :32 ‡are available log 1 ‡ :13 agent creating precisely, according to faults do a year this level. (Further analysis of factors …log‰1 ‡ faults. faults. More allowing (Even though (10), code not arise older affecting to be module dependent, but are be addressed by spontaneously, this is not a tautology:to have only two-thirds on larger data sets but À :09…log‰1 ‡ DEL…c than not otherwise similar code tends The absence of other based requiring the imput of we have10, 13 yet done this. Tuesday, September such faults. and complexity is highly informative.) rt for individual changes given aggregated termsalternative size less powerful) model, using the CDI effo as An many as (and be predicted from symptoms and risk factors for decay? The d the most analysis employs a variant of predictive CDI EFF of (6), odule has estimated to be less than one, the in our data). Statistical 5.1 Temporal Behavior of the Span of C as with the ªsum of touched file sizesº term in (6) omitted. The size of the analyses of the models appear in Section 5.3. The CDI FILES of (3) measures the difficulty o Tˆ 0 is the results are suggestive but, because of the small sample size, how many code units (files) need to be chang not duce faults: 4.2.6 definitive. Effort The model was fit using data from a set of 54 features. implement it. An increase in the span of cha would be One may construct predictors of the effort (person-hours) As noted are the units of system symptomatic of decay, as discussed in Sectio none could required to in Section t2.1, features by fitting regression im (e.g., n change Fig. 3 shows that span is increasing for t functionality plemecall awaiting) by which the system is equations for and extended measurementsaggregated fun...
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