1 Estimating Software Development Using Project Metrics.
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Transcript of 1 Estimating Software Development Using Project Metrics.
1
Estimating Software Estimating Software
DevelopmentDevelopment
Using Project Metrics Using Project Metrics
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Project EstimatingProject Estimating It is Possible to Estimate Software Projects It is Possible to Estimate Software Projects
AccuratelyAccurately Accurate Estimates Take HISTORY and TIMEAccurate Estimates Take HISTORY and TIME Estimation Procedure Must Be Formal StandardsEstimation Procedure Must Be Formal Standards Accurate Estimates Need a Quantitative ToolAccurate Estimates Need a Quantitative Tool Estimates Must be Redone After Every Life Cycle Estimates Must be Redone After Every Life Cycle
PhasePhase
Once All Stakeholders agree on estimation procedures, negotiations can involve Inputs (features & resources) NOT Outputs (time & dollars)
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Activities to be EstimatedActivities to be EstimatedObviousObvious
PlanningPlanning DesignDesign CodingCoding ProceduresProcedures TestingTesting ConversionConversion DocumentatioDocumentatio
nn OperationsOperations MaintenanceMaintenance
Not Obvious
•User/Customers Interaction
•Prototype Demonstrations
•Reviews and Approvals
•Problem/Design Fixes
•Prior Project Support
•Documentation redoes
•Training, vacations, sick, ...
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Danger SignsDanger Signs Estimates the Project Team Does NOT Estimates the Project Team Does NOT
AcceptAccept Estimates Your Experts Do Not AcceptEstimates Your Experts Do Not Accept Estimates that Include OvertimeEstimates that Include Overtime Estimates Assuming Over 80% Estimates Assuming Over 80%
UtilizationUtilization Estimates Without Detailed Task PlansEstimates Without Detailed Task Plans Estimates More Than A “Month” OldEstimates More Than A “Month” Old Estimates NOT UNDER CHANGE Estimates NOT UNDER CHANGE
CONTROLCONTROL
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Measurement & Measurement & MetricsMetrics
... collecting metrics is too hard ... ... collecting metrics is too hard ...
it's too time-consuming ... it's too it's too time-consuming ... it's too
political ... it won't prove anything ...political ... it won't prove anything ...
Anything that you need to Anything that you need to quantify can be measured in quantify can be measured in some way that is superior to some way that is superior to not measuring it at all ..not measuring it at all ..
Tom GilbTom Gilb
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Why do we Why do we Measure?Measure?
To To characterizecharacterize
To evaluateTo evaluate To predictTo predict To improveTo improve
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A Good Manager A Good Manager MeasuresMeasures
measurementmeasurement
What do weWhat do weuse as ause as abasis?basis? • • size?size? • • function?function?
project metricsproject metrics
process metricsprocess metricsprocessprocess
productproduct
product metricsproduct metrics
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Process MetricsProcess Metrics
majority focus on quality achieved majority focus on quality achieved as a consequence of a repeatable as a consequence of a repeatable or managed processor managed process
statistical SQA datastatistical SQA data error categorization & analysiserror categorization & analysis
defect removal efficiencydefect removal efficiency propagation from phase to phasepropagation from phase to phase
reuse datareuse data
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Project MetricsProject Metrics
Effort/time per development taskEffort/time per development task Errors uncovered per review hourErrors uncovered per review hour Scheduled vs. actual milestone datesScheduled vs. actual milestone dates Changes (number) and their Changes (number) and their
characteristicscharacteristics Distribution of effort on development Distribution of effort on development
taskstasks
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Product MetricsProduct Metrics focus on the quality of focus on the quality of
deliverablesdeliverables measures of analysis modelmeasures of analysis model complexity of the designcomplexity of the design
internal algorithmic complexityinternal algorithmic complexity architectural complexityarchitectural complexity data flow complexitydata flow complexity
code measures (e.g., Halstead)code measures (e.g., Halstead) measures of process effectivenessmeasures of process effectiveness
e.g., defect removal efficiencye.g., defect removal efficiency
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Metrics Metrics GuidelinesGuidelines Use common sense and organizational sensitivity Use common sense and organizational sensitivity
when interpreting metrics data.when interpreting metrics data. Provide regular feedback to the individuals and teams Provide regular feedback to the individuals and teams
who have worked to collect measures and metrics.who have worked to collect measures and metrics. Don’t use metrics to appraise individuals.Don’t use metrics to appraise individuals. Work with practitioners and teams to set clear goals Work with practitioners and teams to set clear goals
and metrics that will be used to achieve them.and metrics that will be used to achieve them. Never use metrics to threaten individuals or teams.Never use metrics to threaten individuals or teams. Metrics data that indicate a problem area should not Metrics data that indicate a problem area should not
be considered “negative.” These data are merely an be considered “negative.” These data are merely an indicator for process improvement.indicator for process improvement.
Don’t obsess on a single metric to the exclusion of Don’t obsess on a single metric to the exclusion of other important metrics.other important metrics.
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Normalization for Normalization for MetricsMetricsNormalized data are used to evaluate the process
and the product (but never individual people)
size-oriented normalization —the line of code approach function-oriented normalization —the function point approach
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Typical Size-Oriented Typical Size-Oriented MetricsMetrics errors per KLOC (thousand lines errors per KLOC (thousand lines
of code)of code) defects per KLOCdefects per KLOC $ per LOC$ per LOC page of documentation per KLOCpage of documentation per KLOC errors / person-montherrors / person-month LOC per person-monthLOC per person-month $ / page of documentation$ / page of documentation
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Typical Function-Oriented Typical Function-Oriented MetricsMetrics
$ per FP$ per FP FP per person-monthFP per person-month errors per Function Point (FP)errors per Function Point (FP) defects per FPdefects per FP pages of documentation per pages of documentation per
FPFP
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Why Opt for FP Why Opt for FP Measures?Measures?
independent of programming language uses readily countable characteristics of the "information domain" of the problem does not "penalize" inventive implementations that require fewer LOC than others makes it easier to accommodate reuse and the trend toward object-oriented approaches
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Computing Function Computing Function PointsPointsAnalyze information
domain of the application and develop counts
Weight each count by assessing complexity
Assess influence of global factors that affect the application
Compute function points
Establish count for input domain and system interfaces
Assign level of complexity or weight to each count
Grade significance of external factors, F such as reuse, concurrency, OS, ...
degree of influence: N = Fi
complexity multiplier: C = (0.65 + 0.01 x N)
function points = (count x weight) x C
where:
i
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Analyzing the Information Analyzing the Information DomainDomain
complexity multiplier
function points
number of user inputs number of user outputs number of user inquiries number of files number of ext.interfaces
measurement parameter
3 4 3 7 5
countweighting factor
simple avg. complex
4 5 4 10 7
6 7 6 15 10
= = = = =
count-total
X X X X X
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Taking Complexity into Taking Complexity into AccountAccount
Factors are rated on a scale of 0 (not important) to 5 (very important):
data communications distributed functions heavily used configuration transaction rate on-line data entry end user efficiency
on-line update complex processing installation ease operational ease multiple sites facilitate change
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Typical CalculationTypical CalculationFP CountFP Count 300300
Complexity FactorComplexity Factor 1.2 1.2
FP (Estimated)FP (Estimated) 360 360
Productivity Factor (measured) Productivity Factor (measured) 8 FP/pm 8 FP/pm
$/pm$/pm $8,000$8,000
$/FP$/FP $1,000 $1,000
Estimated Cost of ProjectEstimated Cost of Project $360,000$360,000
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Program Size/Function Program Size/Function PointPoint
Programming LanguageProgramming Language LOC/FPLOC/FP
CC 128128
C++C++ 64 64
COBOLCOBOL 106106
Visual BasicVisual Basic 32 32
SmalltalkSmalltalk 22 22
PowerBuilderPowerBuilder 16 16
SQLSQL 12 12
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Measuring QualityMeasuring Quality
Correctness — the degree to which a Correctness — the degree to which a program operates according to program operates according to specificationspecification
Maintainability—the degree to which a Maintainability—the degree to which a program is amenable to changeprogram is amenable to change
Integrity—the degree to which a Integrity—the degree to which a program is impervious to outside program is impervious to outside attackattack
Usability—the degree to which a Usability—the degree to which a program is easy to useprogram is easy to use
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Defect Removal Defect Removal EfficiencyEfficiency
DRE = (errors) / (errors + defects)
where
errors = problems found before release
defects = problems found after release
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Managing VariationManaging Variation
0
1
2
3
4
5
6
1 3 5 7 9 11 13 15 17 19
Projects
Er, Er
rors
foun
d/
revie
who
urThe mR Control Chart