ezigbo time robbers

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Chapter Six

Project Time and Cost Planning

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Time RobbersThose activities that at first seem to be short and unobtrusive but when they are all added together can completely fill an entire work day

• Task rework• Telephone calls, e‐mail• Land mail• Incomplete work• Lack of needed authority

• Waiting on people• Day‐to‐day administration

• Too many levels of review

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Lack of needed authorityInefficient change procedures

• Casual office conversations

• Poorly run meetings

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Time Robbers continued

• Executive meddling or micro‐management

• Poorly motivated or educated customers

• Vague goals and objectives• Poor time management

• Ill defined project scope

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• Company politics

• Working on under‐funded projects


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Project Time Management ProcessesProject time management describes the processes and methods required to create and

h d l lmanage appropriate schedules to complete the project:

Activity Definition – identifies the lowest level of work on the WBS, “work packages”, that needs to be performed to create the finished product deliverable


deliverableActivity Sequencing – identifying and documenting the logical and sometimes physical relationships among schedule activities


Where Do Schedules Come From?

Step 0. Build the WBSSt 1 D fi A ti iti ( k k )Step 1. Define Activities (work packages)Step 2. Sequence Activities and Assign

proper activity dependencies

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Step 1. Defining ActivitiesDepending on the technique used to create the WBS (refer to chapter 5), typically the work packages are built by decomposing parent activities down intobuilt by decomposing parent activities down into smaller and smaller units of work. Each activity is decomposed into smaller and smaller units until the deliverable can be:

1) assigned to one person who is held responsible for the completion of the task, 2) a time and cost estimate can be accurately generated


2) a time and cost estimate can be accurately generated3) schedule created4) metrics tracked


Activity Characteristics

Status and/or completion is measurable and can be reported easily at any timecan be reported easily at any time

Start and end events are clearly defined and easily communicated

Each activity has a single deliverable

Time and cost is easily estimated


Time and cost is easily estimated


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Activity Characteristics

Activity duration is within acceptable limits no longer than 10 work days This is not a hardlonger than 10 work days. This is not a hard unbreakable rule but a suggested guideline that no activity be defined with an effort longer than two weeks

Work assignments are independent, you


shouldn’t need to interrupt the work in the middle of an activity due to another activity not working as planned


Step 2. Activity Sequencinginvolves identifying and documenting the logical and sometimes physical relationships among schedule activitiesamong schedule activities

Mandatory dependencies: inherent in the nature of the work; write software and then testDiscretionary dependencies: defined by the project team offer the most flexibility; External dependencies: based on work being performed by an entity outside of the organization


performed by an entity outside of the organizationYou must determine correct dependencies to create a realistic schedule


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Schedules

Regardless of which scheduling method is chosen they all strive to graphicallychosen, they all strive to graphically demonstrate the sequential relationships between activities

The two techniques of activity sequencing are the precedence diagram method and the


activity on arrow diagramming method


Arrow Diagramming Method (ADM)

Also called activity‐on‐arrow (AOA) project t k dinetwork diagram

Activities are represented by lines with arrows

Nodes or circles are the starting and ending points of activities

Key Drawback: Can only show finish to start


Key Drawback: Can only show finish‐to‐start dependencies


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Sample Activity‐on‐Arrow (AOA) Network Diagram


• Lines with arrows represent tasks• Circles with words or numbers represent the begin or end of a task


Process for Creating AOA Diagrams1. You draw the first Begin circle or node and then proceed

with the tasks that do not have a predecessor, usually the first tasks to be done on the project. These are shown in the diagram as lines A, K, and F

2 Then you move to the next tasks listed in the WBS in order2. Then you move to the next tasks listed in the WBS in order of precedence. Activity B has a predecessor of A and Activity C has a predecessor of B and so on. Tasks M, G, and L have no successors so we draw their arrows to the End node

3. You add circles at the end of each arrow as an end point. At the end of the process you then number each circle

4. Be prepared as you draw this diagram to draw and then


p p y gerase and redraw as you work your way down the task list

5. You may need to add dummy activities to complete the diagram


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Precedence Diagramming Method (PDM)

uses boxes to represent activities (nodes) and lines with arrows to represent the dependencieslines with arrows to represent the dependencies see example next slide

The task names are for this example shortened to just letters. The lines with arrows are not labeled

Notice that some of the activities (C, F, G, and H)


have more than one predecessor; some only have a successor (Begin) and some only have a predecessor (End)


Sample PD


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Microsoft Project Sample PD


Activity Dependency TypesFinish‐to‐start

Finish coding module before unit testingg gStart‐to‐start

Start on Training Model after Use cases startedFinish‐to‐Finish

Can’t complete training model until User Interface model complete


Start‐to‐FinishPhase out legacy system can’t finish until x days after New system starts acceptance testing


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Information available from Network Analysis of AOA or PDM

Interdependencies of activitiesProject completion timeProject completion timeImpact of late startsImpact of early startsTrade‐offs between resources and time“What if” exercises


Cost of a crash programSlippages in planning/performanceEvaluation of performance


Estimate Activity ResourcesBefore estimating activity durations, you must have a good idea of the quantity and type or level of resources that will be assigned to each activity.

Consider important issues in estimating resources:Consider important issues in estimating resources:

How difficult/complex will it be to complete specific activities on this project?

What is the organization’s history in doing similar activities?

Are the required resources available? Internal or External?


Very important to match the right person with the right task!


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Estimate Activity Resources

Process Activities:Activity resource requirements

Resource calendars

Assigned resources


Techniques for Resource Estimating

1. Expert judgment

2. Analogous

3. Alternatives analysis


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Hints to RememberNever create an initial schedule that requires resources to work overtime, you are already planning for problemsplanning for problemsBe careful of what Ed Yourdon calls the “Marine Corps mentality: Real Programmers Don’t Need Sleep”. Many IT resources especially the new young ones trying to i th i ll d b ill


impress their new colleagues and bosses will not readily admit when they are overwhelmed and need help


Activity Duration Estimating

After defining activities, determining their i i i tsequence, assigning appropriate resources,

the next step in time management is duration estimating

Duration includes the effort (actual amount of time worked on an activity) plus elapsed time


y) p p


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Typical Problems with Estimates

Developing an estimate for a large technology project is a complex task requiring a significantproject is a complex task requiring a significant amount of effort.

Remember that estimates are done at various stages of the project “Progressive Elaboration”

ROM (‐25% to + 75%) or SWAG


Budget (‐10% to + 25%)

Definitive (‐5% to 10%)


Typical Problems continuedMany people doing estimates have little experience doing them. Try to provide training and mentoringPeople have a bias toward underestimation. Review estimates and ask important questions to make sure estimates are not biasedManagement wants a number for a bid or just to look good to superiors, not a real estimate.


Project managers must negotiate with project sponsors to create realistic estimates


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Activity Duration Estimating Methods

1. Analogous

2. Top‐down

3. Bottom‐up

4. Three‐point

5. Simulation


6. COCOMO


Activity Duration EstimatingTo arrive at an estimate of time, you first determine which estimate of work size is needed.As Capers Jones, a noted author in this area, points p pout, the first step in accurately estimating an IT application is determining its size. Over the years, many different techniques have been used, including lines of code, function points, feature points, and so on. Aft th ff t h b i d i f th


After the effort has been sized using one of these methods, time estimates can be applied


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Task Sizing – Lines of CodeHas been one of the most used methodsBased on historical resultsEff t d ll d t ti ft b dEffort, dollars, documentation, software bugs, and number of resourcesAdvantages

Can be very quick and inexpensive to generateCan be done early in the processUniversal metric


Can be generated easily, in most environments automaticallyFacilitate a lessons‐learned process


Lines of Code ‐ DisadvantagesMust compensate for technology differencesCan’t be done well unless relevant history existsMust determine what counts as a line of codeMust determine what counts as a line of codeWhat level of resource is generating the codeNo industry standardsNeed to distinguish between auto‐generated code and original workN d t b ti ll d t d


Needs to be continually updated


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Function Pointsused to estimate time and dollars based on the generated system requirements specificationA function point measures the size of a business function that the new system needs to have such as an input screen or a reportFunction Point analysis can be done at any


Function Point analysis can be done at any point in the project but are not considered accurate until late in the planning phase


Process of Function PointsStep 1: Count the number of business functions within each of the

following categories: user inputs, user outputs, inquiries, data structures, and external interfaces

Step 2 Determine the complexity level of each function as simpleStep 2: Determine the complexity level of each function as simple, medium, or complex. For example output complexity is determined by the number of elements involved, any complex calculations or complex process logic and the number of data structures.

Step 3: Assign weights for each level of complexity within each category

Step 4: Multiply each function by its weight and then sum each product to obtain the total unadjusted function points.

h l d ( )


Step 5: Compute the Value Adjustment Factor (VAF)Step 6: Compute adjusted function point total using the formula

[Unadjusted total x (0.65 + 0.01 x VAF)]


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Example


Next Step: compute the value adjustment factor based on the following table

0 = no effect1 = incidental2 = moderate3 = average4 = significant5 = essential


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Function PointsNext: calculate the total adjusted function points: Unadjusted total x (0.65 + 0.01 x VAF) or

1050 x (0.65 + 0.01 x 40) = 1102.50( )

ResultsEffort = (1.49 hrs effort per f/point) (1102.50) = 1,642.7 hrs

Documentation (.25 pages per f/point) (1102.50) = 275.63 pages

Bugs (.025 bugs per f/point) (1102.50) = 27.5 bugs


User Instructed Rework (.04 per f/point) (1102.50) = 44.1

Dollars ($105.10 per f/point) (1102.50) = $115,872.75


Uses for Function Points# of pages of documentation per FPLevels of effort per FP (person months)evels of effort per FP (person months)Level of expertise per FP (expert, novice)Cost per FP

New derivative called “Feature Points” or


“Object Points”


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Advantages with Function PointsIt is independent of programming language and technology It can be used early in the project life cycle at theIt can be used early in the project life cycle at the end of the requirements discovery phase or design phaseA wealth of research exists to support the processImpact of scope changes easier for all to comprehend and track

k h l


Organizations can track their own results and improve the function point estimatesIt can be used in any development environment


Issues with Function Points

Requires many subjective evaluations (complexity ratings and environmental factors)(complexity ratings and environmental factors)

Accuracy is greatly increased only after the detailed design phase or after a few project iterations have been performed

Takes some time (training) to perfect and can


( g) pvary depending on who is doing the calculations due to personal bias


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Techniques for Estimating

System AnalogyTop down estimatesTop‐down estimates

Package‐Level or “Bottom‐up” Analogy

Three PointSimulation (Monte Carlo)COCOMO Version 2.0 (Parametric Model)


System Analogy

bases a current work package time estimate on the actual time of a work package from aon the actual time of a work package from a similar project already completed

Usually done in a “Top‐down” approach

Have 3 or 4 experts review requirements

Make sure you have the experience and that the


two systems are very similar

Can use time, or LOC, or Function Points


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Package‐Level or Bottom‐Up AnalogyInvolves estimating individual work activities and summing them to get a project total

E h i d h k i i dEach person assigned to that work activity, does the estimate

Can be time intensive to develop

Dependent on each individuals ability to estimate

Combining several independent estimates yields a


g p ybetter estimate than separate estimates. Errors are randomly distributed; statistically speaking


Three PointUse a weighted average approach or beta probability distribution approach to capture three point estimates for each work package

Optimistic, Normal, PessimisticEquations for expected value (E), and the standard deviation (SD) are:

E = (a + 4b + c)/6; SD = (c‐a)/6a the optimistic estimate


a = the optimistic estimateb = normal estimatec = pessimistic estimate


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Three Point

Adds the element of risk into its calculations

SME’s determine three types of estimates:Most Likely

Optimistic

Pessimistic

Next the SME uses the weighted average


Next the SME uses the weighted average formula


Three Point Example

Weighted average =

8 workdays + 4 X 10 workdays + 24 workdays = 12 days8 workdays + 4 X 10 workdays + 24 workdays = 12 days6

where:

optimistic time= 8 days

most likely time = 10 days

pessimistic time = 24 days


Therefore, you’d use 12 days on the schedule instead of 10 when using this technique.


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COCOMOFirst developed by Barry Boehm in 1981Most widely accepted models available todayRevised into version II in 1995Revised into version II in 1995Version II setup to handle new development methodologies; RAD, Iterative/Incremental, COTS packages, O‐O application distribution, frameworks and components, etc.Models available on website and algorithms are


Models available on website and algorithms are published. Commercial software exists


COCOMOConsists of three project types described as:

Organic – small project teams, little innovation, constraints and deadlines are few stable development environmentsand deadlines are few, stable development environments, known familiar technology, few changes expected

Semidetached – medium sized project teams, some innovation, few constraints, tighter deadlines, and more changes expected, still a fairly stable development environment

Embedded largest of the three in all categories large


Embedded – largest of the three in all categories, large project teams, constant innovation, many constraints, very tight deadlines, and many changes expected, complex development environment


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Effort Sizing

Organic:Eff t 2 4 KLOC1 05 h KLOC 1000 li f dEffort = 2.4 x KLOC1.05 where KLOC = 1000 lines of code

Duration = 2.5 x Effort0.38

SemidetachedEffort = 3.0 x KLOC1.12


E b dd d


EmbeddedEffort = 3.6 x KLOC1.2



COCOMO LevelsEarly Application – used mainly for office type applications, after completion of the Analysis phase assumes high level language

Early design – limited version of the application, intended to be used prior to any architecture analysis and relies heavily on function point analysis

Post‐architecture – used to get a view of the project’s


cost once an initial architecture is in place but prior to detailed design.

Most used model, original model


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COCOMO Advantages

Can be Quick

Can be done early in the project

Can be tailored to fit any organization

Can be applied at different phases of the life cycle


Many models exist to aid organizations in getting started


COCOMO IssuesIgnores documentation and other requirements

No compensation for customer attributes p(availability, knowledge, cooperation)

Ignores personnel turnover issues

Based on historical data which may be obsolete

Used only to estimate the development effort, h h f h j ( l i


other phases of the project (planning, implementation) are not accounted for


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Schedule DevelopmentUses results of the other time management processes (activity definition, sequencing, estimating) to determine the start and end date of the project

Also determines the planned start and completion dates for each activity listed on the WBS. The deliverable from this process is the project schedule

Tools used for schedule development:Critical path method

PERT


PERT

Critical Chain

Resource Leveling


Schedule BenefitsCreates a consistent framework which can be followed from project to project and during the execution of the project

Illustrates the interdependencies of each activity on the WBS

Facilitates communication within the project t d b t th t d t k h ld


team and between the team and stakeholders

Aides in the identification of critical activities


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Schedule Benefits

Aides the project manager to evaluate all alternatives and their impact when makingalternatives and their impact when making scheduling changes during the projectReduces the amount of resource scheduling conflictsProvides visibility to those tasks that can or

t b i ll l t k th j t


must be run in parallel to keep the project on trackFacilitates “what‐if” analysis


PERT

The Program Evaluation and Review Technique (PERT) d l d b th U S N i(PERT) was developed by the U.S. Navy in cooperation with the consulting firm Booz‐Allen Hamilton for the Polaris missile/submarine project in 1958 to help organize the activities of 11,000+ contractors


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PERTUses a weighted average approach or betaprobability distribution to capture the three probability distribution to capture the three point estimates discussed in previous lecture (optimistic, most likely, and pessimistic) for activity duration

The PERT weighted averages for each activity dd d h k di h


are added to the network diagram to show the start dates and finish dates for each and the final project end date


Critical Path Method (CPM)

CPM uses the sequence and duration of activities to determine the total projectactivities to determine the total project durationA critical path for a project is the series of activities that determines the earliest time by which the project can be completed


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Critical Path Method (CPM)Produces two key pieces of information: 1. the amount of slack or also referred to as

float for each activity in the schedule and y2. the longest path through the schedule or

said another way the shortest time the project can be completed referred to as the critical path

All activities that fall on this path are


All activities that fall on this path are referred to as critical path activities


Slack

The difference between the earliest time an activity can begin and the latest time anactivity can begin and the latest time an activity can begin without changing the completion date of the projectIn most projects of any size, there is typically only one critical path which means that all of the other paths have tasks with slack but


the other paths have tasks with slack but theoretically a project can have multiple critical paths


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Free Slack

The difference between the earliest time an ti it b i d th l t t tiactivity can begin and the latest time an

activity can begin without changing the completion date of any successor task


Methods to Find the Critical Path

1. Calculate slack for each activity on the WBS i t k diusing a network diagram, or

2. Find the longest path through the network diagram


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Find the Critical Path

1 3 6

A

D

E

G

K

H

5 2

1 9(0,2)

(2,7)

(2,7)

(0 2) (5 6)

(7,9)

(7,9)(9,18)

(4,7)(6 9)

(9,18)(2,3)

Begin

2

4

5

7

F

I

JC

B LEnd

2

4

5

1

7

3

8

3

4

(0,2) (5,6)

(2,6)

(0,4)

(3,8)(0,5)

(5,12)(8,15) (15,18)

(12,15)

(6,9)

(10,18) (18,22)

(18,22)(4,12)


Find Critical Path Calculating Slack

The calculation is performed for each activity in two passes through the entire network diagram for eachpasses through the entire network diagram for each path.

The first pass through starts at the begin node and moves to the end node through each path calculating the ES and EF. The second pass through starts at the end node and moves to the beginning node through each path calculating LS an


LF

Those activities with zero slack are on the critical path


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Find the Longest Path

Path 1 = A, D, G, K, L = 22 daysa , , G, , daysPath 2 = A, E, H, K, L = 19Path 3 = A, E, I, L = 15Path 4 = B, H, K, L = 20Path 5 = B, I, L = 16Path 6 = C, F, J, L = 19


Path A,D,G,K,L is the critical path duration is longest

Critical Path

If one of more activities on the critical path takes longer than planned the whole projecttakes longer than planned, the whole project schedule will slip unless corrective action is takenMisconceptions:

The critical path is not the one with all the criticalactivities; it only accounts for time


activities; it only accounts for timeThe critical path can change as the project progresses!!!!!!!!!


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