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Software Project Management (lecture 4)
The document provides an overview of software project management topics including work breakdown structures (WBS), estimation, scheduling, and planning techniques. It discusses developing a WBS using different partitioning methods and guidelines. Estimation techniques covered include top-down, bottom-up, analogy, expert judgment, and algorithmic methods. The document also addresses converting a project size estimate to an effort estimate in staff-months.
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Software Project Management (lecture 4)
- 1. Software Project Management WBS,Estimation & Scheduling 1
- 2. Today & NextWeek • • • • • Work Breakdown Structures (WBS) Estimation Network Fundamentals PERT & CPM Techniques Gantt Charts 2
- 3. Homework • Distribution ofproject by type – In-house, contract/for-hire, startup • Distribution of project by technology – Web, Windows, No platform • Distribution by industry – Fin. Svcs., Law, Retail • A reminder why no two projects are same 3
- 4. Homework • Most importantelements – Why, who, what, what not – A little bit of when • Make sure it’s clear • Some more re-purposed than others – Occasionally read more like biz plans • Make the stakeholder relationships clear – You, sponsor, user, etc. 4
- 5. Homework • If “forreal” you’d want additional assumptions and scope constraint • The justification or cost-benefit analysis “materializes” in some of the cases • Don’t shortchange downstream activities – Integration, testing, rollout, etc. 5
- 6. Homework • Risks – Businessrisks vs. Project risks • Ex: “lack of market adoption” vs. “inexperienced team” • Formalities • Spell check. • Make sure your name is on first page or footer. • Functionality – “Forgotten” items: user registration, help, security 6
- 7. Homework • Good outof scope items – Internationalization – Search system 7
- 8. Project Considerations • Isinfrastructure setup part of your project? • Assumptions – – – – – What are you counting on? These can be critical to identify Resources expected: equip/people, approvals Availability of partners, connections Outline key limits: • System load: expect an maximum of 100 users 8
- 9. Estimation • “Predictions arehard, especially about the future”, Yogi Berra • 2 Types: Lucky or Lousy? 9
- 10. Planning, Estimating, Scheduling •What’s the difference? • Plan: Identify activities. No specific start and end dates. • Estimating: Determining the size & duration of activities. • Schedule: Adds specific start and end dates, relationships, and resources. 10
- 11. Project Planning: A12 Step Program 1) 2) 3) 4) 5) 6) Set goal and scope Select lifecycle Set org./team form Start team selection Determine risks Create WBS 7) Identify tasks 8) Estimate size 9) Estimate effort 10) Identify task dependencies 11) Assign resources 12) Schedule work 11
- 12. How To Schedule •1. Identify “what” needs to be done – Work Breakdown Structure (WBS) • 2. Identify “how much” (the size) – Size estimation techniques • 3. Identify the dependency between tasks – Dependency graph, network diagram • 4. Estimate total duration of the work to be done – The actual schedule 12
- 13. WBS & Estimation •How did you feel when I asked – “How long will your project take?” • Not an easy answer to give right? • At least not if I were are real customer on a real project • How can you manage that issue? 13
- 14. Partitioning Your Project •You need to decompose your project into manageable chunks • ALL projects need this step • Divide & Conquer • Two main causes of project failure – Forgetting something critical – Ballpark estimates become targets • How does partitioning help this? 14
- 15. Project Elements • AProject: functions, activities, tasks 15
- 16. Work Breakdown Structure:WBS • Hierarchical list of project’s work activities • 2 Formats – Outline (indented format) – Graphical Tree (Organizational Chart) • Uses a decimal numbering system – Ex: 3.1.5 – 0 is typically top level • Includes – Development, Mgmt., and project support tasks • Shows “is contained in” relationships • Does not show dependencies or durations 16
- 17. WBS • Contract WBS(CWBS) – First 2 or 3 levels – High-level tracking • Project WBS (PWBS) – Defined by PM and team members – Tasks tied to deliverables – Lowest level tracking 17
- 18. A Full WBSStructure • Up to six levels (3-6 usually) such as • Upper 3 can be used by customer for reporting (if part of RFP/RFQ) • Different level can be applied to different uses – Ex: Level 1: authorizations; 2: budgets; 3: schedules 18
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- 20. WBS Outline Example 0.0Retail Web Site 1.0 Project Management 2.0 Requirements Gathering 3.0 Analysis & Design 4.0 Site Software Development 4.1 HTML Design and Creation 4.2 Backend Software 4.2.1 Database Implementation 4.2.2 Middleware Development 4.2.3 Security Subsystems 4.2.4 Catalog Engine 4.2.5 Transaction Processing 4.3 Graphics and Interface 4.4 Content Creation 5.0 Testing and Production 20
- 21. WBS Types • ProcessWBS • a.k.a Activity-oriented • Ex: Requirements, Analysis, Design, Testing • Typically used by PM • Product WBS • a.k.a. Entity-oriented • Ex: Financial engine, Interface system, DB • Typically used by engineering manager • Hybrid WBS: both above • This is not unusual • Ex: Lifecycle phases at high level with component or featurespecifics within phases • Rationale: processes produce products 21
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- 25. WBS by PMIProcess Groups 25
- 26. WBS Types • Lessfrequently used alternatives – Organizational WBS • Research, Product Design, Engineering, Operations • Can be useful for highly cross-functional projects – Geographical WBS • Can be useful with distributed teams • NYC team, San Jose team, Off-shore team 26
- 27. Work Packages • Genericterm for discrete tasks with definable end results • Typically the “leaves” on the tree • The “one-to-two” rule • Often at: 1 or 2 persons for 1 or 2 weeks • Basis for monitoring and reporting progress • Can be tied to budget items (charge numbers) • Resources (personnel) assigned • Ideally shorter rather than longer • • • • • Longer makes in-progress estimates needed These are more subjective than “done” 2-3 weeks maximum for software projects 1 day minimum (occasionally a half day) Not so small as to micro-manage 27
- 28. WBS • List ofActivities, not Things • List of items can come from many sources – SOW, Proposal, brainstorming, stakeholders, team • Describe activities using “bullet language” – Meaningful but terse labels • All WBS paths do not have to go to the same level • Do not plan more detail than you can manage 28
- 29. WBS & Methodology •PM must map activities to chosen lifecycle • Each lifecycle has different sets of activities • Integral process activities occur for all – Planning, configuration, testing • Operations and maintenance phases are not normally in plan (considered post-project) • Some models are “straightened” for WBS – Spiral and other iterative models – Linear sequence several times • Deliverables of tasks vary by methodology 29
- 30. WBS Techniques • • • • Top-Down Bottom-Up Analogy Rolling Wave –1st pass: go 1-3 levels deep – Gather more requirements or data – Add more detail later • Post-its on a wall 30
- 31. WBS Techniques • Top-down –Start at highest level – Systematically develop increasing level of detail – Best if • The problem is well understood • Technology and methodology are not new • This is similar to an earlier project or problem – But is also applied in majority of situations 31
- 32. WBS Techniques • Bottom-up –Start at lowest level tasks – Aggregate into summaries and higher levels – Cons • Time consuming • Needs more requirements complete – Pros • Detailed 32
- 33. WBS Techniques • Analogy – – – – BaseWBS upon that of a “similar” project Use a template Analogy also can be estimation basis Pros • Based on past actual experience – Cons • Needs comparable project 33
- 34. WBS Techniques • Brainstorming –Generate all activities you can think of that need to be done – Group them into categories • Both Top-down and Brainstorming can be used on the same WBS • Remember to get the people who will be doing the work involved (buy-in matters!) 34
- 35. WBS – Basisof Many Things • • • • • • Network scheduling Costing Risk analysis Organizational structure Control Measurement 35
- 36. WBS Guidelines Part1 • Should be easy to understand • Some companies have corporate standards for these schemes • Some top-level items, like Project Mgmt. are in WBS for each project – Others vary by project • What often hurts most is what’s missing • Break down until you can generate accurate time & cost estimates • Ensure each element corresponds to a deliverable 36
- 37. WBS Guidelines Part2 • How detailed should it be? – Not as detailed as the final MS-Project plan – Each level should have no more than 7 items – It can evolve over time • What tool should you use? – Excel, Word, Project – Org chart diagramming tool (Visio, etc) – Specialized commercial apps • Re-use a “template” if you have one 37
- 38. Estimations • • Very difficult todo, but needed often Created, used or refined during – – – – – • Strategic planning Feasibility study and/or SOW Proposals Vendor and sub-contractor evaluation Project planning (iteratively) Basic process 1) 2) 3) – Estimate the size of the product Estimate the effort (man-months) Estimate the schedule NOTE: Not all of these steps are always explicitly performed 38
- 39. Estimations • Remember, an“exact estimate” is an oxymoron • Estimate how long will it take you to get home from class tonight – – – – On what basis did you do that? Experience right? Likely as an “average” probability For most software projects there is no such ‘average’ • Most software estimations are off by 25-100% 39
- 40. Estimation • Target vs.Committed Dates • • • • Target: Proposed by business or marketing Do not commit to this too soon! Committed: Team agrees to this After you’ve developed a schedule 40
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- 42. Estimation • Size: – Smallprojects (10-99 FPs), variance of 7% from post-requirements estimates – Medium (100-999 FPs), 22% variance – Large (1000-9999 FPs) 38% variance – Very large (> 10K FPs) 51% variance 42
- 43. Estimation Methodologies • • • • • • Top-down Bottom-up Analogy Expert Judgment Pricedto Win Parametric or Algorithmic Method – Using formulas and equations 43
- 44. Top-down Estimation • Basedon overall characteristics of project – Some of the others can be “types” of top-down (Analogy, Expert Judgment, and Algorithmic methods) • Advantages – Easy to calculate – Effective early on (like initial cost estimates) • Disadvantages – Some models are questionable or may not fit – Less accurate because it doesn’t look at details 44
- 45. Bottom-up Estimation • CreateWBS • Add from the bottom-up • Advantages – Works well if activities well understood • Disadvantages – Specific activities not always known – More time consuming 45
- 46. Expert Judgment • Usesomebody who has recent experience on a similar project • You get a “guesstimate” • Accuracy depends on their ‘real’ expertise • Comparable application(s) must be accurately chosen – Systematic • Can use a weighted-average of opinions 46
- 47. Estimation by Analogy •Use past project – Must be sufficiently similar (technology, type, organization) – Find comparable attributes (ex: # of inputs/outputs) – Can create a function • Advantages – Based on actual historical data • Disadvantages – Difficulty ‘matching’ project types – Prior data may have been mis-measured – How to measure differences – no two exactly same 47
- 48. Priced to Win •Just follow other estimates • Save on doing full estimate • Needs information on other estimates (or prices) • Purchaser must closely watch trade-offs • Priced to lose? 48
- 49. Algorithmic Measures • • • • Lines ofCode (LOC) Function points Feature points or object points Other possible – Number of bubbles on a DFD – Number of of ERD entities – Number of processes on a structure chart • LOC and function points most common – (of the algorithmic approaches) • Majority of projects use none of the above 49
- 50. Code-based Estimates • LOCAdvantages – Commonly understood metric – Permits specific comparison – Actuals easily measured • LOC Disadvantages – – – – Difficult to estimate early in cycle Counts vary by language Many costs not considered (ex: requirements) Programmers may be rewarded based on this • Can use: # defects/# LOC – Code generators produce excess code 50
- 51. LOC Estimate Issues • • • • • Howdo you know how many in advance? What about different languages? What about programmer style? Stat: avg. programmer productivity: 3,000 LOC/yr Most algorithmic approaches are more effective after requirements (or have to be after) 51
- 52. Function Points • Softwaresize s/b measured by number & complexity of functions it performs • More methodical than LOC counts • House analogy – House’s Square Feet ~= Software LOC – # Bedrooms & Baths ~= Function points – Former is size only, latter is size & function • Six basic steps 52
- 53. Function Point Process •1. Count # of biz functions per category – Categories: outputs, inputs, db inquiries, files or data structures, and interfaces • 2. Establish Complexity Factor for each and apply – Simple, Average, Complex – Set a weighting multiplier for each (0->15) – This results in the “unadjusted function-point total” • 3. Compute an “influence multiplier” and apply – It ranges from 0.65 to 1.35; is based on 14 factors • 4. Results in “function point total” – This can be used in comparative estimates 53
- 54. Wideband Delphi • • • • • • • Group consensusapproach Rand corp. used orig. Delphi approach to predict future technologies Present experts with a problem and response form Conduct group discussion, collect anonymous opinions, then feedback Conduct another discussion & iterate until consensus Advantages – Easy, inexpensive, utilizes expertise of several people – Does not require historical data Disadvantages – Difficult to repeat – May fail to reach consensus, reach wrong one, or all may have same bias 54
- 55. Parametric Method Issues •Remember: most projects you’ll run into don’t use these • Which is ‘normal’, so don’t be surprised – Or come-in to new job and say “Hey, let’s use COCOMO” • These are more effective on large projects – Where a past historical base exists • Primary issue for most projects are – Lack of similar projects • Thus lack of comparable data • Catch-22: how to get started 55
- 56. Code Reuse &Estimation • • • • Does not come for free Code types: New, Modified, Reused If code is more than 50% modified, it’s “new” Reuse factors have wide range – Reused code takes 30% effort of new – Modified is 60% of new • Integration effort with reused code almost as expensive as with new code 56
- 57. Effort Estimation • Nowthat you know the “size”, determine the “effort” needed to build it • Various models: empirical, mathematical, subjective • Expressed in units of duration – Man-months (or ‘staff-months’ now) 57
- 58. Effort Estimation • McConnellshows schedule tables for conversion of size to effort • As with parametric size estimation, these techniques perform better with historical data • Again, not seen in ‘average’ projects • Often the size and effort estimation steps are combined (not that this is recommended, but is what often is done) • “Commitment-Based” Scheduling is what is often done – Ask developer to ‘commit’ to an estimate (his or her own) 58
- 59. COCOMO • COnstructive COstMOdel • Allows for the type of application, size, and “Cost Drivers” • Outputs in Person Months • Cost drivers using High/Med/Low & include – Motivation – Ability of team – Application experience • Biggest weakness? – Requires input of a product size estimate in LOC 59
- 60. Estimation Issues • Qualityestimations needed early but information is limited • Precise estimation data available at end but not needed – Or is it? What about the next project? • Best estimates are based on past experience • Politics of estimation: – You may anticipate a “cut” by upper management • For many software projects there is little or none – – – – Technologies change Historical data unavailable Wide variance in project experiences/types Subjective nature of software estimation 60
- 61. Over and UnderEstimation • Over estimation issues – The project will not be funded • Conservative estimates guaranteeing 100% success may mean funding probability of zero. – Parkinson’s Law: Work expands to take the time allowed – Danger of feature and scope creep – Be aware of “double-padding”: team member + manager • Under estimation issues – Quality issues (short changing key phases like testing) – Inability to meet deadlines – Morale and other team motivation issues 61
- 62. Estimation Guidelines • Estimateiteratively! – – – – – Process of gradual refinement Make your best estimates at each planning stage Refine estimates and adjust plans iteratively Plans and decisions can be refined in response Balance: too many revisions vs. too few 62
- 63. Know Your Deadlines •Are they ‘Real Deadlines’? – Tied to an external event – Have to be met for project to be a success – Ex: end of financial year, contractual deadline, Y2K • Or ‘Artificial Deadlines’? – Set by arbitrary authority – May have some flexibility (if pushed) 63
- 64. Estimation “Presentation” • Howyou present the estimation can have huge impact • Techniques • Plus-or-minus qualifiers – 6 months +/-1 month • Ranges – 6-8 months • Risk Quantification – +/- with added information – +1 month of new tools not working as expected – -2 weeks for less delay in hiring new developers • Cases – Best / Planned / Current / Worst cases • Coarse Dates – Q3 02 • Confidence Factors – April 1 – 10% probability, July 1 – 50%, etc. 64
- 65. Other Estimation Factors •Account for resource experience or skill – Up to a point – Often needed more on the “low” end, such as for a new or junior person • Allow for “non-project” time & common tasks – Meetings, phone calls, web surfing, sick days • There are commercial ‘estimation tools’ available – They typically require configuration based on past data 65
- 66. Other Estimation Notes •Remember: “manage expectations” • Parkinson’s Law – “Work expands to fill the time available” • The Student Syndrome – Procrastination until the last minute (cram) 66
- 67. Mythical Man-Month Revisited •Back to notes from class 2 67
- 68. Financial Analysis ofProjects • Financial considerations are often an important consideration in selecting projects • Three primary methods for determining the projected financial value of projects: – Net present value (NPV) analysis – Return on investment (ROI) – Payback analysis 68
- 69. Net Present ValueAnalysis: NPV • NPV: a method of calculating the expected net monetary gain or loss from a project by discounting all expected future cash inflows and outflows to the present point in time • Projects with a positive NPV should be considered if financial value is a key criterion • The higher the NPV, the better 69
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- 71. Return on Investment(ROI) • ROI: income divided by investment ROI = (total discounted benefits - total discounted costs) / discounted costs • The higher the ROI, the better • Many organizations have a required rate of return or minimum acceptable rate of return on investment for projects 71
- 72. Payback Analysis • Anotherimportant financial consideration is payback analysis • The “payback period” is the amount of time it will take to recoup, in the form of net cash inflows, the net dollars invested in a project • Payback occurs when the cumulative discounted benefits and costs are greater than zero • Many organizations want IT projects to have a fairly short payback period 72
- 73. NPV, ROI, PaybackPeriod: Ex 1 73
- 74. NPV, ROI, PaybackPeriod: Ex 2 74
- 75. Weighted Scoring Model •A weighted scoring model is a tool that provides a systematic process for selecting projects based on many criteria • First identify criteria important to the project selection process • Then assign weights (percentages) to each criterion so they add up to 100% • Then assign scores to each criterion for each project • Multiply scores * weights = total weighted scores • The higher the weighted score, the better 75
- 76. Sample Weighted ScoringModel 76
- 77. Homework • McConnell: 9,“Scheduling” • Schwalbe: 5, “Project Time Management” • URLs: See class web site for URLs on PERT/CPM • Create a WBS for your project 77
- 78. WBS Homework • Thefine print • You only need to do this down to level 2 (or 3 if your so inclined or that helps clarify some higher-level activities). Going to level 2 means means start with level 0 (a single node – the name of your project), level 1, the highest level breakdown (4-7 nodes), and one level below that. You can go deeper at your discretion. • As we covered in class, you can use either a process, product or hybrid approach. For most of your projects I suspect the process approach would work best at the highest level. • You can use either Excel, Word, or Project. Follow the standard hierarchical numbering scheme for WBS structures. • Please think this through. You’re the PM now. 78
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Editor's Notes
- #3 No lab today More lab in later term