Rekayasa Perangkat Lunak

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Rekayasa Perangkat Lunak

• Pertemuan IV
• Bab 4 Proses Software Project Metrics

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Lord Kelvin

• Bila anda dapat mengukur apa yang sedang anda
  bicarakan dan mengexpresikan dalam angka, berarti
  anda memahaminyadan bila tidak berarti
  pengetahuan anda belum lengkap

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Pendahuluan

• IEE93 metric as a quantitative measure of
  the degree to which a system, component, or
  process possesses a given attribute.
• A software metric relates the individual measures
  in some way (e.g., the average number of errors
  found per review).
• A software engineer collects measures and
  develops metrics so that indicators will be
  obtained.
• An indicator is a metric or combination of
  metrics that provide insight into the software
  process, a software project, or the product
  itself.

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Metric Example

• Each (4) team must conduct design reviews but is
  allowed to select the type of review that it will
  use.
• Upon examination of the metric, errors found per
  person-hour expended, the project manager notices
  that the two teams using more formal review
  methods exhibit an errors found per person-hour
  expended that is 40 percent higher than the other
  teams.
• Assuming all other parameters equal, this
  provides the project manager with an indicator
  that formal review methods may provide a higher
  return on time investment than another, less
  formal review approach.
• She may decide to suggest that all teams use the
  more formal approach. The metric provides the
  manager with insight. And insight leads to
  informed decision making.

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Indikator proyek

• Memungkinkan manajer proyek
• Memperkirakan status proyek.
• Menelusuri resiko-resiko potensial.
• Menemukan area masalah sebelum semakin kritis.
• Menyesuaikan aliran kerja.
• Mengevaluasi kemempuan tim kontrol kualitas
  atas hasil kerja RPL.

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Penjelasan

• Process sits at the center of a triangle
  connecting three factors that have a profound
  influence on software quality and organizational
  performance.
• Skill motivation of people has been shown to be
  the single most influential factor in quality
  performance.
• Complexity of the product can have a substantial
  impact on quality and team performance.
• Technology (i.e., the software engineering
  methods) that populate the process also has an
  impact.
• The process triangle exists within a circle of
  environmental conditions that include the
  development environment (e.g., CASE tools),
  business conditions (e.g., deadlines, business
  rules), and customer characteristics (e.g., ease
  of communication).

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Set of metrics

• Set of metrics based on the outcomes that can be
  derived from the process.
• Outcomes include measures of
• errors uncovered before release of the software,
• defects delivered to and reported by end-users,
• work products delivered (productivity),
• human effort expended,
• calendar time expended,
• schedule conformance, and others.

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Kesalahan Cacat

• Kesalahan/ error ketidaksempurnaan yang
  ditemukan sebelum disampaikan kepada end-user
• Cacat/ defect ketidaksempurnaan yang ditemukan
  sesudah disampaikan kepada end-user

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Penyebab Cacat/ Defects
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The Intent Of Project Metrics

• To minimize the development schedule by making
  the adjustments necessary to avoid delays and
  mitigate potential problems and risks.
• To assess product quality on an ongoing basis
  and, when necessary, modify the technical
  approach to improve quality.
• As quality improves, defects are minimized, and
  as the defect count goes down, the amount of
  rework required during the project is also
  reduced. This leads to a reduction in overall
  project cost.

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SOFTWARE MEASUREMENT

• Direct measures of the software engineering
  process include cost and effort applied. Direct
  measures of the product include lines of code
  (LOC) produced, execution speed, memory size, and
  defects reported over some set period of time.
• Indirect measures of the product include
  functionality, quality, complexity, efficiency,
  reliability, maintainability, and many other
  "abilities"

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SIZE ORIENTED METRICS
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FUNCTION ORIENTED METRIC
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REKONSILIASI METRIK
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Mengukur Kualitas

• Menurut Gilb
• Correctness. A program must operate correctly or
  it provides little value to its users.
  Correctness is the degree to which the software
  performs its required function. The most common
  measure for correctness is defects per KLOC,
  where a defect is defined as a verified lack of
  conformance to requirements.

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• Maintainability. Maintainability is the ease with
  which a program can be corrected if an error is
  encountered, adapted if its environment changes,
  or enhanced if the customer desires a change in
  requirements.
• A simple time-oriented metric is
  mean-time-tochange (MTTC), the time it takes to
  analyze the change request, design an appropriate
  modification, implement the change, test it, and
  distribute the change to all users.

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• Integrity. This attribute measures a system's
  ability to withstand attacks (both accidental and
  intentional) to its security. Attacks can be made
  on programs, data, and documents.
• Threat is the probability (which can be estimated
  or derived from empirical evidence) that an
  attack of a specific type will occur within a
  given time. Security is the probability (which
  can be estimated or derived from empirical
  evidence) that the attack of a specific type will
  be repelled.
• Integrity summation (1 threat) (1
  security)

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• Usability. Usability is an attempt to quantify
  user-friendliness and can be measured in terms of
  four characteristics
• (1) the physical and or intellectual skill
  required to learn the system,
• (2) the time required to become moderately
  efficient in the use of the system,
• (3) the net increase in productivity measured
  when the system is used by someone who is
  moderately efficient, and
• (4) a subjective assessment (questionnaire) of
  users attitudes toward the system.

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Defect Removal Efficiency (DRE)

• A quality metric that provides benefit at both
  the project and process.
• In essence, DRE is a measure of the filtering
  ability of quality assurance and control
  activities as they are applied throughout all
  process framework activities.
• DRE E/(E D)
• E is the number of errors found before delivery
  of the software to the end-user
• D is the number of defects found after delivery.
• Berapakah DRE ideal???

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Metrik untuk Organisasi Kecil

• Time (hours or days) elapsed from the time a
  request is made until evaluation is complete.
• Effort (person-hours) to perform the evaluation.
• Time (hours or days) elapsed from completion of
  evaluation to assignment of change order to
  personnel.
• Effort (person-hours) required to make the
  change.
• Time required (hours or days) to make the change.
• Errors uncovered during work to make change.
• Defects uncovered after change is released to the
  customer base.

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Teknik Membuat Metrik

1. Identify your business goals.
2. Identify what you want to know or learn.
3. Identify your subgoals.
4. Identify the entities attributes related to
   your subgoals.
5. Formalize your measurement goals.
6. Identify quantifiable questions the related
   indicators.
7. Identify the data elements that you will collect
   to construct the indicators that help answer your
   questions.
8. Define the measures to be used, and make these
   definitions operational.
9. Identify the actions that you will take to
   implement the measures.
10. Prepare a plan for implementing the measures.

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Prioritized Business Goals

• 1. Improve our customers satisfaction with our
  products.
• 2. Make our products easier to use.
• 3. Reduce the time it takes us to get a new
  product to market.
• 4. Make support for our products easier.
• 5. Improve our overall profitability.

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Kesimpulan

• Measurement enables managers and practitioners to
  improve the software process assist in the
  planning, tracking, and control of a software
  project and assess the quality of the product
  (software) that is produced.
• Process metrics enable an organization to take a
  strategic view by providing insight into the
  effectiveness of a software process.
• Data collection, metrics computation, and metrics
  analysis are the three steps that must be
  implemented to begin a metrics program.