Customer Questions. Project Deliverables

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1 Customer Questions Do you understand customer problem and needs? Can you design a system to solve customer problem or satisfy customer needs? How long will it take you to develop the system? How much will it cost to develop the system? Documents Project Deliverables Demonstrations of function Demonstrations of subsystems Demonstrations of accuracy Demonstrations of reliability, performance or security 1

2 Milestones and Activities Activity: takes place over a period of time Milestone: completion of an activity -- a particular point in time Precursor: event or set of events that must occur in order for an activity to start Duration: length of time needed to complete an activity Due date: date by which an activity must be completed PHASE 1 STEP 1 ACTIVITY 1.1 STEP 2 ACTIVITY 1.2 ACTIVITY 1.3 : : PROJECT PHASE 2 STEP 1 STEP 2 : ACTIVITY 2.1 ACTIVITY 2.2 ACTIVITY 3.3 : PHASE n STEP 1 STEP 2 : 2

3 Table 3.1. Phases, steps and activities of building a house. Phase 1: Landscaping the lot Phase 2: Building the house Step 1.1: Step 2.1: Clearing Prepare the and site grubbing Activity 1.1.1: Remove trees Activity 2.1.1: Survey the land Activity 1.1.2: Remove stumps Activity 2.1.2: Request permits Step 1.2: Activity 2.1.3: Excavate for the Seeding the foundation turf Activity 1.2.1: Aerate the soil Activity 2.1.4: Buy materials Activity 1.2.2: Disperse the seeds Step 2.2: Building the exterior Activity 1.2.3: Water and weed Activity 2.2.1: Lay the foundation Step 1.3: Activity 2.2.2: Build the outside walls Planting shrubs and trees Activity 1.3.1: Obtain shrubs and trees Activity 2.2.3: Install exterior plumbing Activity 1.3.2: Dig holes Activity 2.2.4: Exterior electrical work Activity 1.3.3: Plant shrubs and trees Activity 2.2.5: Exterior siding Activity 1.3.4: Anchor the trees and Activity 2.2.6: Paint the exterior mulch around them Activity 2.2.7: Install doors and fixtures Activity 2.2.8: Install roof Step 2.3: Finishing the interior Activity 2.3.1: Install the interior plumbing Activity 2.3.2: Install interior electrical work Activity 2.3.3: Install wallboard Activity 2.3.4: Paint the interior Activity 2.3.5: Install floor covering Activity 2.3.6: Install doors and fixtures 1.1. Survey complete 1.2. Permits issued 1.3. Excavation complete 1.4. Materials on hand 2.1. Foundation laid 2.2. Outside walls complete 2.3. Exterior plumbing complete 2.4. Exterior electrical work complete 2.5. Exterior siding complete 2.6. Exterior painting complete 2.7. Doors and fixtures mounted 2.8. Roof complete 3.1. Interior plumbing complete 3.2. Interior electrical work complete 3.3. Wallboard in place 3.4. Interior painting complete 3.5. Floor covering laid 3.6. Doors and fixtures mounted Table 3.2. Milestones in building a house. 3

4 Install exterior electrical Install exterior siding Paint exterior Install exterior doors and fixtures START Request permits Install exterior plumbing Install roofing Surveying Excavation Buy materials Lay foundation Build outside wall 2.2 Install interior plumbing FINISH 3.1 Install interior electrical 3.2 Install wallboard 3.3 Paint interior Install flooring Install interior doors and fixtures Table 3.3. Activities and time estimates. Activity Time estimate (in days) Step 1: Prepare the site Activity 1.1: Survey the land 3 Activity 1.2: Request permits 15 Activity 1.3: Excavate for the foundation 10 Activity 1.4: Buy materials 10 Step 2: Building the exterior Activity 2.1: Lay the foundation 15 Activity 2.2: Build the outside walls 20 Activity 2.3: Install exterior plumbing 10 Activity 2.4: Exterior electrical work 10 Activity 2.5: Exterior siding 8 Activity 2.6: Paint the exterior 5 Activity 2.7: Install doors and fixtures 6 Activity 2.8: Install roof 9 Step 3: Finishing the interior Activity 3.1: Install the interior plumbing 12 Activity 3.2: Install interior electrical work 15 Activity 3.3: Install wallboard 9 Activity 3.4: Paint the interior 18 Activity 3.5: Install floor covering 11 Activity 3.6: Install doors and fixtures 7 4

5 START FINISH 0 Slack or Float Time Slack time = available time - real time = latest start time - earliest start time 5

6 Table 3.4. Slack time for project activities. Activity Earliest start time Latest start time Slack Finish Build communications software System planning (1.0) System design (2.0) Coding (3.0) Testing(4.0) Delivery (5.0) Review specification(1.1) Review budget (1.2) Review schedule(1.3) Develop plan (1.4) Top-level design (2.1) Prototyping (2.2) User interface (2.3) Detailed design (2.4) 6

7 Description Test of phase 1 Define test cases Write test plan Inspect test plan Integration testing Interface testing Document results System testing Performance tests Configuration tests Document results Start End Jan 1 Jan 8 Jan 15 Jan 22 Jan 29 1 Jan 5 Feb ********************* 1 Jan 8 Jan ****** 9 Jan 22 Jan ******* 9 Jan 22 Jan ******* Feb 5 23 Jan 1 Feb ****** 23 Jan 1 Feb --FFFFF 23 Jan 1 Feb ----FFF Feb 12 Feb 17 2 Feb 17 Feb ******* 2 Feb 17 Feb ----FFF 2 Feb 17 Feb ---FFFF Feb Feb 24 Feb *** ACTIVITY NUMBER DESCRIPTION WBS 1.0 SYSTEM PLANNING TODAY JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1.1 Review specification 1.2 Review budget 1.3 Review schedule 1.4 Develop plan Specification approved Budget approved Schedule approved Plan approved WBS 2.0 SYSTEM DESIGN 2.1 Top-level design Design approved 2.2 Prototyping 2.3 User interface 2.4 Detailed design Completed Duration Float Critical Slippage Start task Design approved Finish task 7

8 Load Overload Underload PROJECTED STAFF-DAYS JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Planned expenditure Actual expenditure TODAY DOLLARS JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 8

9 Earned Value Management Tracks both cost and schedule in a unified manner. Each activity has an estimated cost. When an activity is scheduled to be complete, add that activity s estimated cost to the total called Budged Cost of Work Scheduled (BCWS). When an activity is in fact complete, add that activity s estimated cost to the total called Budged Cost of Work Performed (BCWP). The cost expended to date is the Actual Cost of Work Performed (ACWP). Cost and Schedule Variance These indicate current project status Cost variance: CV = BCWP ACWP Positive indicates costs less than expected Schedule variance: SV = BCWP BCWS Positive indicates ahead of schedule 9

10 Cost and Schedule Indices These can be applied (with caution) to the work remaining to get a predicted final cost and end data Cost Index CI = BCWP/ACWP Schedule Index SI = BCWP/BCWS Cautions About Earned Value More effective if there are several milestones due in each reporting period. If an activity crosses a reporting point, 50% credit to BCWS and to BCWP if the activity has started. This reduces a false indication of behind schedule and overrun. Note it can provide a false indication of being on schedule or underrun. Do not compare BCWS and ACWP. This merely indicates that the spending is to plan, but does not consider the progress toward the goal. 10

11 Project Personnel Key activities requiring personnel: requirements analysis system design program design program implementation testing training maintenance quality assurance Choosing Personnel ability to perform work interest in work experience with similar applications similar tools or languages similar techniques similar development environments training ability to communicate with others ability to share responsibility management skills 11

12 Two people 1 line of communication Three people 3 lines of communication Four people 6 lines of communication Five people : n people 10 lines of communication : n(n-1)/2 lines of communication Work Styles Extroverts: tell their thoughts Introverts: ask for suggestions Intuitives: base decisions on feelings Rationals: base decisions on facts, options 12

13 INTUITIVE INTROVERT INTUITIVE INTROVERT: Asks others Acknowledges feelings RATIONAL INTROVERT: Asks others Decides logically INTUITIVE EXTROVERT: Tells others Acknowledges feelings RATIONAL EXTROVERT: Tells others Decides logically EXTROVERT RATIONAL Myers-Briggs Type Indicator The work of Jung was extended by Myers and Briggs to four dimensions: Extraversion (E) Sensing (S) Thinking (T) Judging (J) Introversion (I) Intuition (N) Feeling (F) Perceiving (P) 13

14 Project Organization Depends on backgrounds and work styles of team members number of people on team management styles of customers and developers Examples: Chief programmer team Egoless approach Chief programmer Assistant chief programmer Senior programmers Librarian Administration Test team Junior programmers 14

15 Table 3.5. Comparison of organizational structures. Highly structured High certainty Repetition Large projects Loosely structured Uncertainty New techniques or technology Small projects Expert judgment Effort Estimation analogy proportion Delphi technique Wolverton model Algorithmic methods: E = (a + bs c ) m(x) Walston and Felix model: E = 5.25S 0.91 Bailey and Basili model: E = S

16 Causes of Inaccurate Estimates Frequent requests for changes Overlooked tasks Users lack of understanding of their own requirements Insufficient analysis when developing the estimate Lack of coordination of systems development, technical services, operations, data administration, and other functions during development Lack of an adequate method or guideline for estimating Key Influences on Estimate Complexity of proposed application Required integration with existing systems Complexity of the programs in the system Size of the system expressed in functions or programs Capabilities and experience of the project team Anticipated frequency or extent of changes Availability of tools 16

17 4x + Size (SLOC) Cost ($) RELATIVE SIZE RANGE 2x 1.5x 1.25x x x x Concept of operations Product Requirementsdesign specification specs. Detailed design specs. Accepted software FeasibilityPlans and Product Detailed requirements design design PHASES AND MILESTONES Development and test Expert Judgment Analogy Compare the proposed system to existing systems. Proportion Compare the proposed system as a factor times an existing system. Delphi Several experts use a formalized system to reconcile their estimates to reach a consensus. 17

18 Table 3.6. Wolverton model cost matrix. Difficulty Type of software OE OM OH NE NM NH Control Input/output Pre/post processor Algorithm Data management Time-critical Table 3.7. Walston and Felix model productivity factors. 1. Customer interface complexity 16. Use of design and code inspections 2. User participation in requirements 17. Use of top-down development definition 3. Customer-originated program design 18. Use of a chief programmer team changes 4. Customer experience with the 19. Overall complexity of code application area 5. Overall personnel experience 20. Complexity of application processing 6. Percentage of development 21. Complexity of program flow programmers who participated in the design of functional specifications 7. Previous experience with the 22. Overall constraints on program s operational computer design 8. Previous experience with the 23. Design constraints on the program s programming language main storage 9. Previous experience with applications 24. Design constraints on the program s of similar size and complexity timing 10. Ratio of average staff size to project 25. Code for real-time or interactive duration (people per month) operation or for execution under severe time constraints 11. Hardware under concurrent 26. Percentage of code for delivery development 12. Access to development computer open under special request 13. Access to development computer closed 14. Classified security environment for computer and at least 25% of programs and data 15. Use of structured programming 27. Code classified as nonmathematical application and input/output formatting programs 28. Number of classes of items in the database per 1000 lines of code 29. Number of pages of delivered documentation per 1000 lines of code 18

19 Bailey-Basili Technique Minimize standard error estimate to produce an equation such as: E = S 1.16 Adjust initial estimate based on the ratio of errors. If R is the ratio between the actual effort, E, and the predicted effort, E, then the effort adjustment is defined as ERadj = R 1 if R > 1 = 1 1/R if R < 1 Then adjust the initial effort estimate E: Eadj = (1 + ERadj)E if R > 1 = E/(1 + ERadj) if R < 1 Table 3.8. Bailey-Basili effort modifiers. Total methodology (METH) Cumulative complexity (CPLX) Cumulative experience (EXP) Tree charts Customer interface Programmer qualifications complexity Top-down design Application complexity Programmer machine experience Formal documentation Program flow complexity Programmer language experience Chief programmer teams Internal communication complexity Programmer application experience Formal training Database complexity Team experience Formal test plans External communication complexity Design formalisms Customer-initiated program design changes Code reading Unit development folders 19

20 COCOMO Model: Stages of Development application composition: prototyping to resolve high-risk user interface issues size estimates in object points early design: to explore alternative architectures and concepts size estimates in function points postarchitecture: development has begun size estimates in lines of code TABLE 3.9 Three Stages of COCOMO II Stage 1: Stage 2: Application Early Stage 3: Model Aspect Composition Design Post-architecture Size Applicatio n Function points (FP) FP and language or source lines points and language of code (SLOC) Reuse Implicit in Equivalent SLOC as Equivalent SLOC as function of model function of other other variables variables Requirements Implicit in % change expressed as % change expressed as a change model a cost factor cost factor Maintenance Application Function of ACT, software Function of ACT, software Point understanding, understanding, Annual unfamiliarity unfamiliarity Change Traffic Scale (c) in to 1.23, depending 0.91 to 1.23, depending on nominal effort on precedentedness, precedentedness, conformity, equation conformity, early early architecture, risk resolution, architecture, risk team cohesion, and SEI process resolution, team maturity cohesion, and SEI process maturity Product cost None Complexity, required Reliability, database size, drivers reusability documentation needs, required reuse, and product complexity Platform cost None Platform difficulty Execution time constraints, main drivers storage constraints, and virtual machine volatility Personnel None Personnel capability Analyst capability, applications cost drivers and experience experience, programmer capability, programmer experience, language and tool experience, and personnel continuity Project cost None Required development Use of software tools, required drivers schedule, development development schedule, and environment multisite development 20

21 For Screens Number of views contained Table Application point complexity levels. Number and source of data tables Total < 4 Total < 8 Total 8+ (<2 (2-3 (>3 server, server, server, >5 <3 3-5 client) client) client) For Reports Number of sections contained Number and source of data tables Total < 4 Total < 8 Total 8+ (<2 (2-3 (>3 server, server, 3- server, <3 5 client) >5 client) client) <3 simple simple medium 0 or 1 simple simple medium 3-7 simple medium difficult 2 or 3 simple medium difficult 8 + medium difficult difficult 4 + medium difficult difficult Table Complexity weights for application points. Object type Simple Medium Difficult Screen Report GL component Table Productivity estimate calculation. Developers experience and capability Very low Low Nominal High Very high CASE maturity and capability Very low Low Nominal High Very high Productivity factor Table Tool use categories. Category Very low Low Nominal High Very high Meaning Edit, code, debug Simple front-end, back-end CASE, little integration Basic life-cycle tools, moderately integrated Strong, mature life-cycle tools, moderately integrated Strong, mature, proactive life-cycle tools, well-integrated with processes, methods, reuse 21

22 Machine Learning Techniques Example: case-based reasoning user identifies new problem as a case system retrieves similar cases from repository system reuses knowledge from previous cases system suggests solution for new case Example: neural network cause-effect network trained with data from past history Problem complexity Novelty of application Use of design tools Effort Team size Input layer Intermediate layers Output layer 22

23 Evaluating Models Mean magnitude of relative error (MMRE) absolute value of mean of [(actual - estimate)/actual] goal: should be.25 or less Pred(x/100): percentage of projects for which estimate is within x% of the actual goal: should be.75 or greater for x =.25 Table Summary of model performance. Model PRED(0.25) MMRE Walston-Felix Basic COCOMO Intermediate COCOMO Intermediate COCOMO (variation) Bailey-Basili Pfleeger SLIM Jensen COPMO General COPMO

24 Planning Planning Testing Coding Coding Other Brooks Yourdon Risk Management Requirements Risk impact: the loss associated with the event Risk probability: the likelihood that the event will occur Risk control: the degree to which we can change the outcome Risk exposure = (risk probability) x (risk impact) 24

25 Three strategies for risk reduction avoiding the risk: change requirements for performance or functionality transferring the risk: transfer to other system, or buy insurance assuming the risk: accept and control it risk leverage = difference in risk exposure divided by cost of reducing the risk Boehm s top ten risk items Personnel shortfalls Unrealistic schedules and budgets Developing the wrong functions Developing the wrong user interfaces Gold-plating Continuing stream of requirements changes Shortfalls in externally-performed tasks Shortfalls in externally-furnished components Real-time performance shortfalls Straining computer science capabilities 25

26 Risk assessment Risk identification Risk analysis Risk prioritization Checklist Decomposition Assumption analysis Decision driver analysis System dynamics Performance models Cost models Network analysis Decision analysis Quality risk factor analysis Risk management Risk control Risk reduction Risk management planning Risk resolution Risk exposure Compound risk reduction Buying information Risk avoidance Risk transfer Risk reduction leverage Development process Risk element planning Risk plan integration Risk mitigation Risk monitoring and reporting Risk reassessment Project plan contents project scope project schedule project team organization technical description of system project standards and procedures quality assurance plan configuration management plan documentation plan data management plan resource management plan test plan training plan security plan risk management plan maintenance plan 26

27 Information System Example Apply COCOMO II Ratings for Piccadilly Screens and Reports Name Screen or Report Complexity Weight Booking Screen Simple 1 Ratecard Screen Simple 1 Availability Screen Medium 2 Sales Report Medium 5 The text shows how this analysis proceeds to give an estimate. Real-Time Example The text suggests that risk analysis might have avoided the problem. In fact the developers had concluded that the risk was greater for modifying the SRI software than to use it as is. It was apparently not recognized that the alignment routine would be executed during flight. 27

CSCI 5828: Foundations of Software Engineering

CSCI 5828: Foundations of Software Engineering Lecture 9 and 10: Planning the Software Project Slides created by Pfleeger and Atlee for the SE textbook Some modifications to the original slides have been