SDPM - Lecture 4 - Activity planning and resource allocation

Leiden Institute of Advanced Computer Science

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System’s Development and Project Management – Activity planning and resource allocation

Prof. Dr. Thomas Bäck

Leiden Institute of Advanced Computer Science Dates

Feb. 1 14:45 – 17:30 Introduction, Project Description Feb. 2 13:45 – 16:30 STEP WISE Approach to Project Planning Feb. 9 13:10 – 15:45 Selecting an Appropriate Software Dev.

Approach Feb. 15 14:45 – 17:30 Activity Planning and Resource Allocation Feb. 16 15:15 – 18:00 Software Effort Estimation Feb. 22 14:45 – 17:30 Risk management, project escalation Feb. 23 13:45 – 16:30 Project monitoring and control Mar. 1 14:45 – 17:00 Exam Mar. 2 13:45 – 16:30 Software Quality Assurance Mar. 8 14:45 – 17:30 Managing People; Contract Management Mar. 9 13:45 – 16:30 Various Mar. 15 14:45 – 17:30 Trade Fair

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STEP WISE overview

3 System‘s Development and Project Management - Prof. Dr. Thomas Bäck

1. Identify project objectives 0. Select Project 2. Identify project infrastructure

3. Analyze pr. characteristics

4. Identify products and activities

5. Estimate effort for activity

6. Identify activity risks

7. Allocate resources

8. Review / publicize plan 9. Execute plan

10. Lower level planning

For each activity

Review lower level detail


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Sequencing and scheduling objectives

!   ‘Time is nature’s way of stopping everything happening at once’

!  Recall… !   The difference between elapsed time and effort !   Examples: baking bread, brewing beer


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Sequencing and scheduling objectives (cont’d)

!   Feasibility assessment !   Is the project possible within time and resource constraints?

!   Resource allocation !   What are the most effective ways of allocating resources to

the project?

!   Detailed costing !   When are expenditures likely to take place?

!   Motivation !   Co-ordination

!   When does staff has to be transferred between projects?


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Main stages for sequencing and scheduling

1.  Ideal activity plan: what activities need to be carried out in which order?

2.  Activity risk analysis: aimed at identifying potential (resource) problems

3.  Resource allocation 4.  Schedule production: indicates planned start

and completion dates and resources for each activity


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Identifying activities

!  Activity-based approach !   Ad-hoc vs. Work Breakdown Structure (WBS)

•  WBS may be based on project’s products, in turn based on a simple list of final deliverables, and a set of activities required to produce that product.

!   May be redefined as project proceeds

!  Product-based approach !   Product Breakdown Structure (PBS) !   Product Flow Diagram (PFD)

•  Can easily be transformed into ordered list of activities

!  Hybrid approach


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Activity-on-node

Do A

Do C

Do B

Do D

Activity-on-arrow Do A Do B

Do C Do D

Graphical representation


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Techniques History

!  Originally developed in the 50s !  Critical Path Method (CPM) !  Program Evaluation Review Technique (PERT) !  CPM using Activity-on-Node !  PERT using Activity-on-Arrow !  Alternative: Precedence Networks

!   Activity-on-Node !   Links represent precedence or sequencing

requirements.


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Events vs. activities

Prepare breakfast Eat breakfast

activities

events

!   Event = a point in time (used in activity-on-arrow networks) !   Has no duration !   E.g the start or end of an activity

!   Activity = a task or an action with a recognizable start and finish and a duration


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Remarks

!  No loops in a network! !   Iterations may occur in practice, but cannot be

represented !   Solution: Repeat set of activities

!  No dangles !   Dangling activities indicate logical errors !   Add a final completion activity as a remedy


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Next Step after creation of the Logical Network

!  Think about the “when” … !  CPM primary objectives:

!   Planning such that project is completed as early as possible

!   Identifying activities likely to affect overall end date !   Dummy activities (dotted lines on a network diagram)

•  Zero duration, no resources •  Aid the layout


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!   Activity ‘write report software’ !   Earliest start (ES) !   Earliest finish (EF) = ES + duration !   Latest finish (LF) = latest task can be completed without

affecting project end; latest start = LF – duration !   Activity span = LF – ES

(maximum time allowable for activity)

Earliest finish

Earliest start

Latest start

Latest finish

activity

Start and finish times


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Example

!   Earliest start = day 5 !   Latest finish = day 30 !   Duration = 10 days

!   Earliest finish = ? !   Latest start = ?

Float = LF - ES - duration

What is it in this case?


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Activity description

Activity label Duration

ES

LS

EF

LF Activity span: LF-ES Float: LF-ES-Duration

Notation


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Complete for previous example

A

5

25 15

30

15

10

20 Write report

software


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EF = day 7

EF = day10

ES = day10

!   Earliest start date for the current activity = earliest finish date for the previous

!   When there is more than one previous activity, take the latest earliest finish

!   Note ‘day 7’ = end of work on day 7

Earliest start date


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Example: ES for activity G?

A

B

C

D

F

E

G

ES = day 0

Duration 5

Duration 6

Duration 10

Duration 9

Duration 8

Duration 3

Duration 4


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Complete the table Activity ES Duration EF

A

B

C

D

E

F

G

0 5 5

5 6 11 5 10 15 5 9 14

15 8 23 14 3 17

23 4 27


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Latest start dates

!  Start from the last activity !  Latest finish (LF) for last activity = earliest

finish (EF) !  Work backwards !  Latest finish for current activity = latest start

for the following !  More than one following activity - take the

earliest LS !  Latest start (LS) = LF for activity - duration


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A

B

C

D

F

E

G

ES = day 0

Duration 5

Duration 6

Duration 10

Duration 9

Duration 8

Duration 3

Duration 4

Example: LS for all activities?


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Activity ES Dur EF LS LF

A

B

C

D

E

F

G

Complete the table

0 5 5

5 6 11 5 10 15 5 9 14

15 8 23 14 3 17

23 4 27 27 23

20 11 15 5

23 20 23 15

15 9

5 0


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Float = Latest finish - earliest start -

duration

ES

Latest start

activity LF

FLOAT

Float

Image Source: Wikimedia


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Activ. ES Dur EF LS LF Float

A

B

C

D

E

F

G

Complete the table

0 5 5

5 6 11 5 10 15 5 9 14

15 8 23 14 3 17

23 4 27 27 23

20 11 15 5

23 20 23 15

15 9

5 0

4 0 6

0 6

0

0

LF-ES-Dur


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Critical path: Defines project duration

!  Note the path through network with zero floats

!  Critical path: any delay in an activity on this path will delay whole project

!  Can there be more than one critical path? !  Can there be no critical path? !  Sub-critical paths


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!  Activity schedule - indicating start and completion dates for each activity

!  Resource schedule - indicating dates when resources needed + level of resources

!  Cost schedule showing accumulative expenditure

Types of schedules


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Resources

!  These include !   Labor !   Equipment (e.g. workstations) !   Materials !   Space !   Services

!  Time - elapsed time can often be reduced by adding more staff

!  Money - used to buy the other resources


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!   Identify the resources needed for each activity

!   Identify resource types - individuals are interchangeable within the group (e.g. ‘VB programmers’ as opposed to ‘software developers’)

!  Allocate resource types to activities and examine the resource histogram

Resource allocation


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Week 1 2 3 4 5 6 7

1

2

3

4

5

Sta

ff re

quire

d Resource histogram: systems analysts


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!  Can be resolved by: !   Delaying one of the activities

•  Taking advantage of float to change start date •  Delaying start of one activity until finish of the other

activity that resource is being used on - puts back project completion

!   Moving resource from a non-critical activity !   Bringing in additional resource - increases costs

Resource clashes


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!   Critical path activities !   Other activities with little float !   When a short activity would allow a number of larger

activities to start

Priorities

4 days

30 days

15 days

15 days

10 days resource clash


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Burman’s priority list: Activities that can proceed at same time

1.  Shortest critical activity 2.  Critical activities 3.  Shortest non-critical activity 4.  Non-critical activities with least float 5.  Non-critical activities


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!  Need to maximize percentage usage of resources i.e. reduce idle periods between tasks

!  Need to balance costs against early completion date

!  Need to allow for contingency !   Scheduling can create new critical paths

Resource usage


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!   Staff costs: salaries as well as other direct costs of employment

!   Overheads: expenditure that organization incurs which cannot be directly related to individual projects

!   Usage charge: e.g. processing time

Cost schedules

Schedule is usually presented on a weekly or cumulative basis

Education

SDPM - Lecture 4 - Activity planning and resource allocation