POM L9

Question 1

What are the components of estimation?

Answer 1

• Cost: Personnel (in person day, person days x cost rate), Material, Extra costs
• Scope: Number and Complexity of requirements
• Time: Development time (duration = effort/people ), project duration, dependencies
• Infrastructure

Question 2

Top-Down and Bottom-Up estimation

Answer 2

Top-Down Approach
• Estimate effort for the whole project
• Breakdown to different project phases and work
products
Bottom-Up Approach
• Start with effort estimates for tasks on the lowest possible level
• Aggregate the estimates until top activities are reached

top-down if you don’t have WBS (Work Breakdown Structure), bottom up if you do

Question 3

What are the problems with Traditional Estimation Techniques

Answer 3

• focus on the completion and not on delivery of features
• wrong focus in schedules review (reviewers look for overlooked activities not features)
• saving time through reducing quality

Question 4

Dependency Diagrams

Answer 4

formal notation that helps in analysis of complex schedule
Consist of
- Event
- Activity (amount of work)
- Span time (amount of time, parameters: availability of resources, parallelizability of the activity)

Question 5

Critical Path (forward path analysis) and Slack time (back path analysis) in dependency diagrams

Answer 5

• critical path: sequence of activities that take the longest time to complete
• Noncritical path: a sequence of activities that can be delayed and the project can still finish in the shortest time possible
• Slack time: the maximum delay time

Question 6

Path Types in Dependency Graphs

Answer 6

Critical path: path in which all slack times are zero
Noncritical path: Any path with at least one nonzero slack time activity
Overcritical path: at least one activity has a negative slack time

Question 7

Types of Dependencies

Answer 7

FS (Finish-to-start): B cannot start till A finishes
SS: B cannot start until A starts
FF: B cannot finish until A finishes
SF: B cannot finish until A starts

Question 8

Start and Finish Dates

Answer 8

• Earliest start date (ES)
• Earliest finish date (EF)
• Latest start date (LS)
• Latest finish date (LS)

Question 9

Dependency constraints

Answer 9

• As Soon As Possible (ASAP)
• Start No Earlier Than
  (SNET)
• Start No Later Than (SNLT)
• Must Start On (MSO)
• As Late As Possible (ALAP)
• Finish No Earlier Than (FNET)
• Finish No Later Than (FNLT)
• Must Finish On (MFO)

Question 10

What’s milestone view specially good for

Answer 10

Good for introduction of project and high executive briefings

Question 11

Activities view

Answer 11

Good for documentation and during developer meetings

Question 12

Two types of Gantt chart

Answer 12

• Person entered view (when managing experienced teams)
• Activity centred view (to identify teams working on same activity, when managing beginners)

Gantt chart is easy to read, and when combined with milestones is good for reviews

Question 13

PERT (Program Evaluation and Report Technique)

Answer 13

Algorithm:
• Assign optimistic, pessimistic and most likely estimates
for the span times of each activity
• Compute the probability that the project duration falls within specified limits
allows to use multiple estimates per project activity

Good for clear illustration of task dependencies

Question 14

Fudge factor

Answer 14

A fudge factor is the extra amount of time you add to
your best estimate of span time “just to be safe”
Don’t use fudge factors!
Reason: Parkinson’s law

Question 15

Backing In

Answer 15

You start at the last milestone of the project and work your way back toward the starting milestone, while estimating durations that will add up to the available time

Question 16

What is COCOMOD and what are its problems ?

Answer 16

COnstructive COst MOdel
#Top Down Approach to estimate cost, efor n schedule based on size and complexity
#Comparing with finished project
#No Req. changes during development.
#• Calculate effort
  • Effort = A * KDSIB
  • Calculate development time
  • Time = C * EffortD
Problems:
-Judgment is required 
-Estimation can differ by the factor of 4 (Cone of uncertainty)
-Some important factors are not considered (Skill, travel ...)

Question 17

Explain the Playing Poker approach !

Answer 17

Estimation of the difficulty of a project, Each memer gets to choose a difficulty level of a task then the result of all is show it repeats itself till every one agree on a same result
+wisdom of crowd
-long discussion

Question 18

Why is estimation a hard task?

Answer 18

#Discussions may take long time
#There is not enough knowledge about the developing environment

Question 19

What does the Cone of Uncertainty show?

Answer 19

#There is not enough knowledge about the project at the beginning
#Many characteristics of a project become clear only after some time
#estimation results can deviate from actual effort by a factor of 4.

Question 20

What should be considered when estimating?

Answer 20

#Project budget
#The locations where development takes place
#Project duration