Ch23 project planning

Chapter 23 – Project planning
10/12/2014 Chapter 23 Project Planning 1

Topics covered
 Software pricing
 Plan-driven development
 Project scheduling
 Agile planning
 Estimation techniques
 COCOMO cost modeling

Project planning
 Project planning involves breaking down the work into
parts and assign these to project team members,
anticipate problems that might arise and prepare
tentative solutions to those problems.
 The project plan, which is created at the start of a
project, is used to communicate how the work will be
done to the project team and customers, and to help
assess progress on the project.

Planning stages
 At the proposal stage, when you are bidding for a
contract to develop or provide a software system.
 During the project startup phase, when you have to plan
who will work on the project, how the project will be
broken down into increments, how resources will be
allocated across your company, etc.
 Periodically throughout the project, when you modify
your plan in the light of experience gained and
information from monitoring the progress of the work.

Proposal planning
 Planning may be necessary with only outline software
requirements.
 The aim of planning at this stage is to provide
information that will be used in setting a price for the
system to customers.
 Project pricing involves estimating how much the
software will cost to develop, taking factors such as staff
costs, hardware costs, software costs, etc. into account

Project startup planning
 At this stage, you know more about the system
requirements but do not have design or implementation
information
 Create a plan with enough detail to make decisions
about the project budget and staffing.
 This plan is the basis for project resource allocation
 The startup plan should also define project monitoring
mechanisms
 A startup plan is still needed for agile development to
allow resources to be allocated to the project

Development planning
 The project plan should be regularly amended as the
project progresses and you know more about the
software and its development
 The project schedule, cost-estimate and risks have to be
regularly revised

Software pricing

Software pricing
 Estimates are made to discover the cost, to the
developer, of producing a software system.
 You take into account, hardware, software, travel, training and
effort costs.
 There is not a simple relationship between the
development cost and the price charged to the customer.
 Broader organisational, economic, political and business
considerations influence the price charged.

Factors affecting software pricing
Factor Description
Contractual terms A customer may be willing to allow the developer to retain
ownership of the source code and reuse it in other projects.
The price charged may then be less than if the software
source code is handed over to the customer.
Cost estimate
uncertainty
If an organization is unsure of its cost estimate, it may
increase its price by a contingency over and above its
normal profit.
Financial health Developers in financial difficulty may lower their price to
gain a contract. It is better to make a smaller than normal
profit or break even than to go out of business. Cash flow is
more important than profit in difficult economic times.

Factors affecting software pricing
Factor Description
Market opportunity A development organization may quote a low price
because it wishes to move into a new segment of the
software market. Accepting a low profit on one project may
give the organization the opportunity to make a greater
profit later. The experience gained may also help it develop
new products.
Requirements volatility If the requirements are likely to change, an organization
may lower its price to win a contract. After the contract is
awarded, high prices can be charged for changes to the
requirements.

Pricing strategies
 Under pricing
 A company may underprice a system in order to gain a contract
that allows them to retain staff for future opportunities
 A company may underprice a system to gain access to a new
market area
 Increased pricing
 The price may be increased when a buyer wishes a fixed-price
contract and so the seller increases the price to allow for
unexpected risks

Pricing to win
 The software is priced according to what the software
developer believes the buyer is willing to pay
 If this is less that the development costs, the software
functionality may be reduced accordingly with a view to
extra functionality being added in a later release
 Additional costs may be added as the requirements
change and these may be priced at a higher level to
make up the shortfall in the original price

Plan-driven development

Plan-driven development
 Plan-driven or plan-based development is an approach
to software engineering where the development process
is planned in detail.
 Plan-driven development is based on engineering project
management techniques and is the ‘traditional’ way of managing
large software development projects.
 A project plan is created that records the work to be
done, who will do it, the development schedule and the
work products.
 Managers use the plan to support project decision
making and as a way of measuring progress.

Plan-driven development – pros and cons
 The arguments in favor of a plan-driven approach are
that early planning allows organizational issues
(availability of staff, other projects, etc.) to be closely
taken into account, and that potential problems and
dependencies are discovered before the project starts,
rather than once the project is underway.
 The principal argument against plan-driven development
is that many early decisions have to be revised because
of changes to the environment in which the software is to
be developed and used.

Project plans
 In a plan-driven development project, a project plan sets
out the resources available to the project, the work
breakdown and a schedule for carrying out the work.
 Plan sections
 Introduction
 Project organization
 Risk analysis
 Hardware and software resource requirements
 Work breakdown
 Project schedule
 Monitoring and reporting mechanisms

Project plan supplements
Plan Description
Configuration management plan Describes the configuration management procedures
and structures to be used.
Deployment plan Describes how the software and associated hardware
(if required) will be deployed in the customer’s
environment. This should include a plan for migrating
data from existing systems.
Maintenance plan Predicts the maintenance requirements, costs, and
effort.
Quality plan Describes the quality procedures and standards that
will be used in a project.
Validation plan Describes the approach, resources, and schedule used
for system validation.

The planning process
 Project planning is an iterative process that starts when
you create an initial project plan during the project
startup phase.
 Plan changes are inevitable.
 As more information about the system and the project team
becomes available during the project, you should regularly revise
the plan to reflect requirements, schedule and risk changes.
 Changing business goals also leads to changes in project plans.
As business goals change, this could affect all projects, which
may then have to be re-planned.

The project planning process

Planning assumptions
 You should make realistic rather than optimistic
assumptions when you are defining a project plan.
 Problems of some description always arise during a
project, and these lead to project delays.
 Your initial assumptions and scheduling should therefore
take unexpected problems into account.
 You should include contingency in your plan so that if
things go wrong, then your delivery schedule is not
seriously disrupted.

Risk mitigation
 If there are serious problems with the development work
that are likely to lead to significant delays, you need to
initiate risk mitigation actions to reduce the risks of
project failure.
 In conjunction with these actions, you also have to re-
plan the project.
 This may involve renegotiating the project constraints
and deliverables with the customer. A new schedule of
when work should be completed also has to be
established and agreed with the customer.

Project scheduling

Project scheduling
 Project scheduling is the process of deciding how the
work in a project will be organized as separate tasks,
and when and how these tasks will be executed.
 You estimate the calendar time needed to complete each
task, the effort required and who will work on the tasks
that have been identified.
 You also have to estimate the resources needed to
complete each task, such as the disk space required on
a server, the time required on specialized hardware,
such as a simulator, and what the travel budget will be.

Project scheduling activities
 Split project into tasks and estimate time and resources
required to complete each task.
 Organize tasks concurrently to make optimal
use of workforce.
 Minimize task dependencies to avoid delays
caused by one task waiting for another to complete.
 Dependent on project managers intuition and
experience.

The project scheduling process

Scheduling problems
 Estimating the difficulty of problems and hence the cost
of developing a solution is hard.
 Productivity is not proportional to the number of people
working on a task.
 Adding people to a late project makes it later because of
communication overheads.
 The unexpected always happens. Always allow
contingency in planning.

Schedule presentation
 Graphical notations are normally used to illustrate the
project schedule.
 These show the project breakdown into tasks. Tasks
should not be too small. They should take about a week
or two.
 Calendar-based
 Bar charts are the most commonly used representation for
project schedules. They show the schedule as activities or
resources against time.
 Activity networks
 Show task dependencies

Project activites
 Project activities (tasks) are the basic planning element.
Each activity has:
 a duration in calendar days or months,
 an effort estimate, which shows the number of person-days or
person-months to complete the work,
 a deadline by which the activity should be complete,
 a defined end-point, which might be a document, the holding of a
review meeting, the successful execution of all tests, etc.

Milestones and deliverables
 Milestones are points in the schedule against which you
can assess progress, for example, the handover of the
system for testing.
 Deliverables are work products that are delivered to the
customer, e.g. a requirements document for the system.

Tasks, durations, and dependencies
Task Effort (person-
days)
Duration (days) Dependencies
T1 15 10
T2 8 15
T3 20 15 T1 (M1)
T4 5 10
T5 5 10 T2, T4 (M3)
T6 10 5 T1, T2 (M4)
T7 25 20 T1 (M1)
T8 75 25 T4 (M2)
T9 10 15 T3, T6 (M5)
T10 20 15 T7, T8 (M6)
T11 10 10 T9 (M7)
T12 20 10 T10, T11 (M8)

Activity bar chart

Staff allocation chart

Agile planning

Agile planning
 Agile methods of software development are iterative
approaches where the software is developed and
delivered to customers in increments.
 Unlike plan-driven approaches, the functionality of these
increments is not planned in advance but is decided
during the development.
 The decision on what to include in an increment depends on
progress and on the customer’s priorities.
 The customer’s priorities and requirements change so it
makes sense to have a flexible plan that can
accommodate these changes.

Agile planning stages
 Release planning, which looks ahead for several months
and decides on the features that should be included in a
release of a system.
 Iteration planning, which has a shorter term outlook, and
focuses on planning the next increment of a system. This
is typically 2-4 weeks of work for the team.

Approaches to agile planning
 Planning in Scrum
 Covered in Chapter 3
 Based on managing a project backlog (things to be
done) with daily reviews of progress and problems
 The planning game
 Developed originally as part of Extreme Programming (XP)
 Dependent on user stories as a measure of progress in the
project

Story-based planning
 The planning game is based on user stories that reflect the features
that should be included in the system.
 The project team read and discuss the stories and rank them in
order of the amount of time they think it will take to implement the
story.
 Stories are assigned ‘effort points’ reflecting their size and difficulty
of implementation
 The number of effort points implemented per day is measured giving
an estimate of the team’s ‘velocity’
 This allows the total effort required to implement the system to be
estimated

The planning game

Release and iteration planning
 Release planning involves selecting and refining the
stories that will reflect the features to be implemented in
a release of a system and the order in which the stories
should be implemented.
 Stories to be implemented in each iteration are chosen,
with the number of stories reflecting the time to deliver
an iteration (usually 2 or 3 weeks).
 The team’s velocity is used to guide the choice of stories
so that they can be delivered within an iteration.

Task allocation
 During the task planning stage, the developers break
down stories into development tasks.
 A development task should take 4–16 hours.
 All of the tasks that must be completed to implement all of the
stories in that iteration are listed.
 The individual developers then sign up for the specific tasks that
they will implement.
 Benefits of this approach:
 The whole team gets an overview of the tasks to be completed in
an iteration.
 Developers have a sense of ownership in these tasks and this is
likely to motivate them to complete the task.

Software delivery
 A software increment is always delivered at the end of
each project iteration.
 If the features to be included in the increment cannot be
completed in the time allowed, the scope of the work is
reduced.
 The delivery schedule is never extended.

Agile planning difficulties
 Agile planning is reliant on customer involvement and
availability.
 This can be difficult to arrange, as customer
representatives sometimes have to prioritize other work
and are not available for the planning game.
 Furthermore, some customers may be more familiar with
traditional project plans and may find it difficult to engage
in an agile planning process.

Agile planning applicability
 Agile planning works well with small, stable development
teams that can get together and discuss the stories to be
implemented.
 However, where teams are large and/or geographically
distributed, or when team membership changes
frequently, it is practically impossible for everyone to be
involved in the collaborative planning that is essential for
agile project management.

Estimation techniques

Estimation techniques
 Organizations need to make software effort and cost
estimates. There are two types of technique that can be
used to do this:
 Experience-based techniques The estimate of future effort
requirements is based on the manager’s experience of past
projects and the application domain. Essentially, the manager
makes an informed judgment of what the effort requirements are
likely to be.
 Algorithmic cost modeling In this approach, a formulaic approach
is used to compute the project effort based on estimates of
product attributes, such as size, and process characteristics,
such as experience of staff involved.

Estimate uncertainty

Experience-based approaches
 Experience-based techniques rely on judgments based
on experience of past projects and the effort expended in
these projects on software development activities.
 Typically, you identify the deliverables to be produced in
a project and the different software components or
systems that are to be developed.
 You document these in a spreadsheet, estimate them
individually and compute the total effort required.
 It usually helps to get a group of people involved in the
effort estimation and to ask each member of the group to
explain their estimate.

Problem with experience-based approaches
 The difficulty with experience-based techniques is that a
new software project may not have much in common
with previous projects.
 Software development changes very quickly and a
project will often use unfamiliar techniques such as web
services, application system configuration or HTML5.
 If you have not worked with these techniques, your
previous experience may not help you to estimate the
effort required, making it more difficult to produce
accurate costs and schedule estimates.

Algorithmic cost modelling
 Cost is estimated as a mathematical function of
product, project and process attributes whose
values are estimated by project managers:
 Effort = A ´ SizeB ´ M
 A is an organisation-dependent constant, B reflects the
disproportionate effort for large projects and M is a multiplier
reflecting product, process and people attributes.
 The most commonly used product attribute for cost
estimation is code size.
 Most models are similar but they use different values for
A, B and M.

Estimation accuracy
 The size of a software system can only be known
accurately when it is finished.
 Several factors influence the final size
 Use of reused systems and components;
 Programming language;
 Distribution of system.
 As the development process progresses then the size
estimate becomes more accurate.
 The estimates of the factors contributing to B and M are
subjective and vary according to the judgment of the
estimator.

Effectiveness of algorithmic models
 Algorithmic cost models are a systematic way to
estimate the effort required to develop a system.
However, these models are complex and difficult to use.
 There are many attributes and considerable scope for
uncertainty in estimating their values.
 This complexity means that the practical application of
algorithmic cost modeling has been limited to a relatively
small number of large companies, mostly working in
defense and aerospace systems engineering.

COCOMO cost modeling

COCOMO cost modeling
 An empirical model based on project experience.
 Well-documented, ‘independent’ model which is not tied
to a specific software vendor.
 Long history from initial version published in 1981
(COCOMO-81) through various instantiations to
COCOMO 2.
 COCOMO 2 takes into account different approaches to
software development, reuse, etc.

COCOMO 2 models
 COCOMO 2 incorporates a range of sub-models that
produce increasingly detailed software estimates.
 The sub-models in COCOMO 2 are:
 Application composition model. Used when software is
composed from existing parts.
 Early design model. Used when requirements are available but
design has not yet started.
 Reuse model. Used to compute the effort of integrating reusable
components.
 Post-architecture model. Used once the system architecture has
been designed and more information about the system is
available.

COCOMO estimation models

Application composition model
 Supports prototyping projects and projects where there
is extensive reuse.
 Based on standard estimates of developer productivity in
application (object) points/month.
 Takes software tool use into account.
 Formula is
 PM = ( NAP ´ (1 - %reuse/100 ) ) / PROD
 PM is the effort in person-months, NAP is the number of
application points and PROD is the productivity.

Application-point productivity
Developer’s
experience
and capability
Very low Low Nominal High Very high
ICASE maturity
and capability
Very low Low Nominal High Very high
PROD
(NAP/month)
4 7 13 25 50

Early design model
 Estimates can be made after the requirements have
been agreed.
 Based on a standard formula for algorithmic models
 PM = A ´ SizeB ´ M where
 M = PERS ´ RCPX ´ RUSE ´ PDIF ´ PREX ´ FCIL ´ SCED;
 A = 2.94 in initial calibration,
 Size in KLOC,
 B varies from 1.1 to 1.24 depending on novelty of the project,
development flexibility, risk management approaches and the
process maturity.

Multipliers
 Multipliers reflect the capability of the developers, the
non-functional requirements, the familiarity with the
development platform, etc.
 RCPX - product reliability and complexity;
 RUSE - the reuse required;
 PDIF - platform difficulty;
 PREX - personnel experience;
 PERS - personnel capability;
 SCED - required schedule;
 FCIL - the team support facilities.

The reuse model
 Takes into account black-box code that is reused without
change and code that has to be adapted to integrate it
with new code.
 There are two versions:
 Black-box reuse where code is not modified. An effort estimate
(PM) is computed.
 White-box reuse where code is modified. A size estimate
equivalent to the number of lines of new source code is
computed. This then adjusts the size estimate for new code.

Reuse model estimates 1
 For generated code:
 PM = (ASLOC * AT/100)/ATPROD
 ASLOC is the number of lines of generated code
 AT is the percentage of code automatically generated.
 ATPROD is the productivity of engineers in integrating this code.

Reuse model estimates 2
 When code has to be understood and integrated:
 ESLOC = ASLOC * (1-AT/100) * AAM.
 ASLOC and AT as before.
 AAM is the adaptation adjustment multiplier computed from the
costs of changing the reused code, the costs of understanding
how to integrate the code and the costs of reuse decision
making.

Post-architecture level
 Uses the same formula as the early design model but
with 17 rather than 7 associated multipliers.
 The code size is estimated as:
 Number of lines of new code to be developed;
 Estimate of equivalent number of lines of new code computed
using the reuse model;
 An estimate of the number of lines of code that have to be
modified according to requirements changes.

The exponent term
 This depends on 5 scale factors (see next slide). Their
sum/100 is added to 1.01
 A company takes on a project in a new domain. The
client has not defined the process to be used and has
not allowed time for risk analysis. The company has a
CMM level 2 rating.
 Precedenteness - new project (4)
 Development flexibility - no client involvement - Very high (1)
 Architecture/risk resolution - No risk analysis - V. Low .(5)
 Team cohesion - new team - nominal (3)
 Process maturity - some control - nominal (3)
 Scale factor is therefore 1.17.

Scale factors used in the exponent computation
in the post-architecture model
Scale factor Explanation
Architecture/risk resolution Reflects the extent of risk analysis carried out. Very low means little
analysis; extra-high means a complete and thorough risk analysis.
Development flexibility Reflects the degree of flexibility in the development process. Very low
means a prescribed process is used; extra-high means that the client
sets only general goals.
Precedentedness Reflects the previous experience of the organization with this type of
project. Very low means no previous experience; extra-high means that
the organization is completely familiar with this application domain.
Process maturity Reflects the process maturity of the organization. The computation of
this value depends on the CMM Maturity Questionnaire, but an
estimate can be achieved by subtracting the CMM process maturity
level from 5.
Team cohesion Reflects how well the development team knows each other and work
together. Very low means very difficult interactions; extra-high means
an integrated and effective team with no communication problems.

Multipliers
 Product attributes
 Concerned with required characteristics of the software product
being developed.
 Computer attributes
 Constraints imposed on the software by the hardware platform.
 Personnel attributes
 Multipliers that take the experience and capabilities of the people
working on the project into account.
 Project attributes
 Concerned with the particular characteristics of the software
development project.

The effect of cost drivers on effort estimates
Exponent value 1.17
System size (including
factors for reuse and
requirements volatility)
128,000 DSI
Initial COCOMO estimate
without cost drivers
730 person-months
Reliability Very high, multiplier = 1.39
Complexity Very high, multiplier = 1.3
Memory constraint High, multiplier = 1.21
Tool use Low, multiplier = 1.12
Schedule Accelerated, multiplier = 1.29
Adjusted COCOMO
estimate
2,306 person-months

The effect of cost drivers on effort estimates
Exponent value 1.17
Reliability Very low, multiplier = 0.75
Complexity Very low, multiplier = 0.75
Memory constraint None, multiplier = 1
Tool use Very high, multiplier = 0.72
Schedule Normal, multiplier = 1
Adjusted COCOMO
estimate
295 person-months

Project duration and staffing
 As well as effort estimation, managers must estimate the
calendar time required to complete a project and when
staff will be required.
 Calendar time can be estimated using a COCOMO 2
formula
 TDEV = 3 ´ (PM)(0.33+0.2*(B-1.01))
 PM is the effort computation and B is the exponent computed as
discussed above (B is 1 for the early prototyping model). This
computation predicts the nominal schedule for the project.
 The time required is independent of the number of
people working on the project.

Staffing requirements
 Staff required can’t be computed by diving the
development time by the required schedule.
 The number of people working on a project varies
depending on the phase of the project.
 The more people who work on the project, the more total
effort is usually required.
 A very rapid build-up of people often correlates with
schedule slippage.

Key points
 The price charged for a system does not just depend on its
estimated development costs and the profit required by the
development company. Organizational factors may mean that the
price is increased to compensate for increased risk or decreased to
gain competitive advantage.
 Software is often priced to gain a contract and the functionality of the
system is then adjusted to meet the estimated price.
 Plan-driven development is organized around a complete project
plan that defines the project activities, the planned effort, the activity
schedule and who is responsible for each activity.

Key points
 Project scheduling involves the creation of various graphical
representations of part of the project plan. Bar charts, which show
the activity duration and staffing timelines, are the most commonly
used schedule representations.
 A project milestone is a predictable outcome of an activity or set of
activities. At each milestone, a formal report of progress should be
presented to management. A deliverable is a work product that is
delivered to the project customer.
 The agile planning game involves the whole team in project
planning. The plan is developed incrementally and, if problems
arise, it is adjusted so that software functionality is reduced instead
of delaying the delivery of an increment.

Key points
 Estimation techniques for software may be experience-based, where
managers judge the effort required, or algorithmic, where the effort
required is computed from other estimated project parameters.
 The COCOMO II costing model is a mature algorithmic cost model
that takes project, product, hardware and personnel attributes into
account when formulating a cost estimate.

Ch23 project planning

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Ch23 project planning