1. Software Project Management Task Estimating and Scheduling
Sequencing to Estimating/Scheduling
Gantt Charts
Resource Management

2. Activity Duration Estimating
After defining activities and determining sequence, the next steps are estimating and mapping to a calendar
“Bottom-up” Estimating
Estimate each activity individually and sum as you go
Some folks add an “overhead” fudge factor
Scheduling
Map tasks onto fixed points in time
Typically represented using Gantt Charts
Course Technology, 1999

3. Bottom-up Estimating How do you construct per task estimates?
Weighted average formula:
optimistic time + 4X most likely time + pessimistic time 6
Example:
Suppose you had a task you estimate at 10 days, but have some risk associated with it?
Weighted Calculation:
8 workdays + 4 X 10 workdays + 24 workdays = 12 days
where 8 = optimistic time, 10 = most likely time, 24 = pessimistic time
When constructing your schedule, consider the risk factor associated with the worst case!
Course Technology, 1999

4. PERT Example Revisited
The dates as shown here are the result of some probabilistic estimate
For example, Task 4 with a 6 day estimate may
have had best, expected, worst estimates of 1, 7, 8

5. Gantt Charts Gantt charts Symbols include:
Provide a standard format for displaying project schedule information
Lists project activities and their corresponding start and finish dates in a calendar format
Start with your WBS and refine
Symbols include:
A black diamond: milestones or significant events on a project with zero duration
Thick black bars: summary tasks
Lighter horizontal bars: tasks
Arrows: dependencies between tasks
Course Technology, 1999

6. Sample Tracking Gantt Chart
white diamond: slipped milestone
two bars: planned and actual times
The actual color and pattern may vary by tool
Course Technology, 1999

7. Schedule “Slack” Slack - flexibility in your schedule
Free slack or free float is the amount of time an activity can be delayed without delaying the early start of any immediately following activities
Total slack or total float is the amount of time an activity may be delayed from its early start without delaying the planned project finish date
Formula 1:
The buffer in your plan can be computed as the total calendar time minus the critical path duration
Formula 2:
The buffer can be calculated as the latest date by which you can start minus the earliest date on the calendar you can start
CONTENT BLOCKED Due to copyright infringement.
Slack time = available time - real time
Slack = latest start time - earliest start time

8. Example Free and Total Float or Slack for Project X
Course Technology, 1999

9. Computing Early and Late Times
Forward Pass: determine early start (ES) and early finish (EF) times for each task
Work from left to right
Adding times in each path
Rule: when several tasks converge, the ES for the next task is the largest of preceding EF times
Backward Pass: determine the last finish (LF) and last start (LS) times
Start at the end node
Compute the bottom pair of numbers
Subtract duration from connecting node’s earliest start time

10. Example: Compute ES, EF, LS, LF

11. Example: Solution

12. Scheduling Make Schedule Trade-offs
Knowing the critical path helps you make trade-offs
Consider all inputs to your schedule
Estimates - You cannot violate the constraints of the PERT
Change dependencies (F-S, S-S, etc.)
Change estimates once given
Resourcing
Outsourcing
Other constrained resources
So what tradeoffs?
Remember the diamond!!!
Scope - can you reduce what you have to deliver (& therefore do?)
Quality - skimping on quality implies you can work “faster”
Time - can you extend the due date and open up slack?
Cost - can you invest in more resources?
Time
Quality
Cost
Expectations
Scope

13. Project Schedule Shortfalls
If a project is falling behind, think of the “levers” you can pull:
Add more time
Add more people - Beware the “Mythical Man Month”!
Revise expectations
Address the critical path!
Techniques:
Shortening durations of critical tasks for adding more resources or changing their scope
Crashing tasks by obtaining the greatest amount of schedule compression for the least incremental cost
Fast tracking tasks by doing them in parallel or overlapping them - implies modifying dependencies
Course Technology, 1999

14. Shortening Project Schedules
Original
schedule
Shortened duration
Overlapped
tasks
Course Technology, 1999

15. Project Resource Organization
Depends on backgrounds & work styles of team members
Extroverts: tell their thoughts
Introverts: ask for suggestions
Intuitives: base decisions on feelings
Rationals: base decisions on facts, options
Resource Staffing
Mapping skill types to functional needs and support
Sophisticated models understand skill level, experience
Responsibility Assignment Matrix (RAM) and/or Skills Matrix (SM)
RAM
A resource planning tool
Who does What
Can be for both planning and tracking
Identify authority, accountability, responsibility
Who: can be individual, team or department
Can have totals/summary at end of row/column
CONTENT BLOCKED Due to copyright infringement. SM
Another resource planning tool
Resources on one axis, skills on other
Skills can high level or very specific
Cells can be X’s or numeric

16. RAM Examples
Simple RAM
Skills Matrix (SM)
RAM with
stakeholder

17. Resource Plan – Staffing Levels
 Resource Staffing Levels:
Looks kinda like your EVA eh?
GANTT Chart View:
per person, per task
Matrix View:
Name
DEP
Proj1
Proj2
Proj3
Proj4
Proj5 0%
50%
Joe
Eng
Sue
Bob ?
25%
75%
100%?
Bill
100%
Row
Ops
Julie
Cindy
33%
Tim
Barry
Miles
67%
Paula
Peter
133%
Total
200%
83%?
83%
91%
108%
700%

18. Issues and Summary WBS - Project and Task Scope
Task Activity Networks, Precedence Charts, PERT
Task dependencies and duration estimates
Scheduling, Gantt - Map to “real-time”
Considers all constraints on the project
May have slack to reduce risk (but at what cost?)
Resource Planning
Pick your model (RAM or SM), pick your view
Track – living document throughout your project!
Issues
Granularity
Resilience to change
Too much work when it falls out of date anyway?