chapter 5 software project planning slides by omar garcia

Chapter 5Software Project Planning

Slides by Omar garcia

CSCI 425/925 Version 3 2

Agenda

Motivation Introduction Software Project Estimation Decomposition techniques Empirical Estimation Make/Buy Decision About Project Manager The project plan Quiz

Project Planning Objectives

The objective of software project planning is to provide a framework that enables the manager to make reasonable estimates of resources, cost, and schedule.

These estimates are made within a limited time frame at the beginning of a software project and should be updated regularly as the project progresses. In addition, estimates should attempt to define best case and worst case scenarios so that project outcomes can be

bounded.


The Steps

Scoping—understand the problem and the work that must be done

Estimation—how much effort? how much time? Risk—what can go wrong? how can we avoid it?

what can we do about it? Schedule—how do we allocate resources along

the timeline? what are the milestones? Control strategy—how do we control quality?

how do we control change?


Write it Down!

SoftwareSoftwareProjectProject

PlanPlan

Project ScopeProject ScopeEstimatesEstimatesRisksRisksScheduleScheduleControl strategyControl strategy


Scoping the Problem Identify the customer Customer discussions:

– Who is the end user [often not the customer]?– Who has the authority to accept the finished

product?– What problem are we addressing?– What documentation will be required?– When does he believe he needs the product?– Where is the work to be done?– Why does he need the product?– How will the product be developed / acquired?

Identify the systems environment Identify necessary tools Identify potential re-use

Software Scope

Software scope describes among others:function, performance, constraints, interfaces, and reliability.

Observations on Estimation

Estimate what?resources, cost, and schedule for a software engineering effort

What does it require?experience, access to good historical information, and … the courage to commit to quantitative predictions when qualitative information is all that exists.

Estimation carries inherent risk and this risk leads to

uncertainty.

Observations on Estimation

Factors:Project complexity has a strong effect on the uncertainty inherent in planning. Complexity is a relative measure: beginner or experienced team.Project size can affect the accuracy and efficacy of estimates. As size increases, the interdependency among various elements of the software grows rapidly.

Murphy's law: "What can go wrong will go wrong"—and if there are more things that can fail, more things will

fail. Degree of structural uncertainty: structure refers to the ease with which the task can be subdivided.

Resources

Software Project Estimation

In the early days of computing, software costs constituted a small percentage of the overall computer-based system cost.

Today, software is the most expensive element of virtually all computer-based systems.

Software cost and effort estimation will never be an exact science.

Too many variables—human, technical, environmental, political—can affect the ultimate cost of software and effort applied to develop it.


To achieve reliable cost and effort estimates, a number of options arise:

Delay estimation until late in the project (obviously, we can achieve 100% accurate estimates after the project is complete!).

Base estimates on similar projects that have already been completed.

Use relatively simple decomposition techniques to generate project cost and effort estimates.

Use one or more empirical models for software cost and effort estimation.


Critics:First option is not practical. Cost estimates must be provided "up front." Second option: unfortunately, past experience has not always been a good indicator of future results.

Ideally, the techniques noted for each option should be applied in tandem; each used as a cross-check for the other.

Software Project EstimationDecomposition techniques take a "divide and conquer" approach to software project estimation; cost and effort estimation can be performed in a stepwise fashion.

Empirical estimation models can be used to complement decomposition techniques and offer a potentially valuable estimation approach in their own right.

A model is based on experience is d = f (vi)

where d is one of a number of estimated values (e.g., effort, cost, project duration) and vi are selected independent parameters (e.g., estimated LOC or FP).

Automated estimation tools implement one or more decomposition techniques or empirical models. In such systems, the characteristics of the development organization (e.g., experience, environment) and the software to be developed are

described. Cost and effort estimates are derived from these data.

Automated Estimation Tools

Automated estimation tools allow the planner to estimate cost and effort and to perform "what-if" analyses for important project variables such as delivery date or staffing.

All automated tools perform the following six generic functions:

•Sizing of project deliverables. The "size" of one or more software work products is estimated.

– Output: e.g., screen, reports,

–The software itself (e.g., KLOC),

– Functionality delivered (e.g., function points),

– Descriptive information (e.g. documents).

Automated Estimation Tools•Predicting staffing levels. The number of people who will be available to do the work is specified.

•Predicting software effort. Estimation tools use one or more models that relate the size of the project deliverables to the effort required to produce them.

•Predicting software cost. Given the results of step 4, costs can be computed by allocating labor rates to the project activities noted in step 2.

•Predicting software schedules. When effort, staffing level, and project activities are known, a draft schedule can be produced by allocating labor across software engineering activities based on

recommended models for effort distribution.


Estimation Guidelines

estimate using at least two techniquesget estimates from independent sourcesavoid over-optimism, assume difficultiesyou've arrived at an estimate, sleep on itadjust for the people who'll be doing the

job, they have the highest impact


The Make/Buy Decision

Software engineering managers are faced with a make/buy decision. It may be further complicated by a number of acquisition options:

(1) software may be purchased (or licensed) off-the-shelf,

(2) "full-experience" or "partial-experience" software components may be acquired and then modified and integrated to meet specific needs, or

(3) software may be custom built by an outside contractor to meet the purchaser's specifications.


The Make/Buy DecisionFor more expensive software products, the following guidelines can be applied:

1. Develop specifications for function and performance of the desired software. Define measurable characteristics whenever possible.

2. Estimate the internal cost to develop and the delivery date.

3a.Select three or four candidate applications that best meet your specifications.

3b. Select reusable software components that will assist in constructing the required application.

4. Develop a comparison matrix that presents a head-to-head comparison of key functions. Alternatively, conduct benchmark tests to compare candidate software.

5. Evaluate each software package or component based on past product quality, vendor support, product direction, reputation, and the like.

6. Contact other users of the software and ask for opinion.


Nature of a Project Manager

More than a person who wants to deliver a project on time and within budget

More than a person who can best apply the tools for time and resource management

A true project manager must have ‘a fire in the belly’, to do everything required to make the project a success


Nature of a Project Manager

How do you become a Project Manager?

Specialist training is required as well as gaining experience by working on bids or projects and then manage progressively larger projects

Project Management, in many ways, is like parenting. You learn from what you see as your parent’s mistakes


Project Plan1 Introduction

<copy and paste directly from requirements specification>2 Project Estimates

<describe estimation technique><table of module name, estimated effort>

3 Risk Management <identify all risks><table of risk, severity, consequences, detection, remediation>

4 Schedule<identify each task (1 week granularity)><identify starting and ending triggers for each task><list of tasks on project time line><include opportunities to review work products>

5 Resources5.1 Resources Available

<table of person name intended hours task assignment>5.2 Resource Loading

<diagram mapping resource allocation onto the schedule>


Quiz What should you do with this plan?

A- Stick it on the shelf and ignore it

B- Make it hard to change

C- Change it every week to reflect how things are going

D- Express it electronically where it is

accessible to change

under configuration control

know who changed it

know why they changed it


Group Assignment for the lab The problem

– Describe the arrangements made by phone to identify your partner and yourself for the first time at the airport after a long e-romance.

Restrictions– No mobile phones are allowed.– After setting the arrangements on the phone, both leave

to the airport ( no more talking). The maximum length for this assignment is 350 words

(no more than a page) The whole group may get an extra point. Hand this in before Wednesday 17 March 5 p.m.

chapter 5 software project planning slides by omar garcia

Documents